Bitcoin Myths · #16 of 20

Bitcoin Is Centralized by Miners

What Miners Actually Do, and What They Do Not

Mining requires expensive hardware, substantial electricity, and ongoing operational investment. The machines that run it are specialized computers competing to solve a mathematical puzzle roughly every ten minutes. The winner attaches a bundle of transactions to the solution and broadcasts it to the network as a new block. At that point, the miner’s role in that block is complete. What happens next is not up to them.

Every full node^{A computer running Bitcoin software that stores the entire ledger and independently checks every transaction against the rules.} on the Bitcoin network independently receives that block and checks it against the protocol rules. Does the proof-of-work^{A consensus rule where miners spend real energy to add blocks, making the chain’s history expensive to rewrite.} solution meet the current difficulty target? Do all the transactions spend only funds that exist? Is the block reward within the allowed limit? Does any transaction attempt a double-spend^{An attempt to spend the same bitcoin twice. The node network prevents it by agreeing on one shared transaction history.}? A single violation on any of these checks, and the node rejects the block, with no appeals process and no escalation path. Every node makes the determination independently.

Saifedean Ammous, author of The Bitcoin Standard, frames the relationship in plain terms. Miners sell a commodity to the network. That commodity is blocks. The nodes are the buyers, and they are also the judges. Miners invest capital upfront and recover it only by producing blocks that the nodes accept. They are structurally incapable of dictating terms to their own customers.

This is not a criticism of miners. Mining is what secures the network. The energy cost of proof-of-work is what makes the ledger costly to attack. But securing the network is a different function from governing it. The distinction matters because it answers the question of what Bitcoin’s decentralization actually consists of. It is not a uniform distribution of hash power but a structural separation between the people who produce blocks and the people who decide which blocks count.

The 2017 Block Size War: Evidence Over Theory

Arguments about decentralization in Bitcoin can become abstract quickly. The 2017 Block Size War is useful precisely because it is not abstract. It is a documented event with a clear outcome.

In 2017, a coalition of large mining operations and industry companies signed the New York Agreement, committing to a protocol change that would increase Bitcoin’s block size. The miners involved controlled more than 80% of Bitcoin’s hash rate^{The total computing power securing the Bitcoin network. A higher hash rate means more security.} at the time. The argument for the change was framed as necessary for scaling. The implicit assumption behind it was that controlling the majority of hash rate meant controlling the direction of the protocol.

The node operators did not agree. Individual Bitcoin users running their own nodes, distributed across the world, refused to upgrade to software that accepted the larger block size. They were under no obligation to do so. There is no central authority in Bitcoin that can instruct node operators to adopt a new version of the protocol. Each node operator decides independently which software to run. And the overwhelming majority decided that the New York Agreement did not represent a change they would accept.

The miners’ proposed chain was ignored by the network. Exchanges and services that had signalled support for the fork backed away when it became clear the node network would not follow. By the end of 2017, the fork proposal had been abandoned. The block size remained at one megabyte. Bitcoin continued on the chain the nodes had maintained throughout.

The full picture is somewhat wider than node operators alone. Exchanges, wallet developers, and economically significant users who chose not to adopt the new software also contributed to the outcome. Hash rate majority was not sufficient to override the economic and social consensus governing which rules the network follows. Every group whose participation matters had to agree, and they did not.

Jonathan Bier’s The Blocksize War documents the full sequence of events in detail. The takeaway relevant to this myth is simple. The people with the most hash rate tried to change Bitcoin and failed, because rule enforcement did not sit with them.

Why the Math Makes Cheating Futile

The 2017 war showed the outcome, and the mechanism underneath explains why it was close to inevitable.

Producing a block costs energy and hardware. Verifying a block costs almost nothing. Every full node checks every block automatically, and the computational work involved is trivial compared to the work of mining. Adam Livingston, in The Bitcoin Age, describes this as asymmetric verification. It is expensive to cheat but efficient to verify. Any participant can confirm a block’s validity with minimal effort. This is not a governance design choice. It is a consequence of how proof-of-work and public-key cryptography interact.

The practical implication is that mining power cannot overwhelm the verification layer. A miner who produces a block claiming a larger reward than the protocol allows, or including a double-spend, or violating the 21 million supply cap, does not need to be voted down or overruled by a committee. Every honest node on the network simply rejects the block. The miner’s work is wasted, the reward goes unpaid, and the violating block never appears in anyone’s chain.

Matthew Kratter, in A Beginner’s Guide to Bitcoin, explains the node’s role in plain terms. Full nodes maintain a complete copy of the blockchain and independently verify every transaction and block against the protocol rules. No single node has special privileges. No node’s decision carries more weight than any other’s. The network reaches consensus not through hierarchy but through identical rule enforcement applied independently across thousands of participants.

The supply cap makes the argument concrete for anyone new to it. Consider what miners would actually do if they controlled Bitcoin. The most obvious move is also the most self-interested one. They give themselves more Bitcoin. The asset is worth significant money. If the operators of the hardware could simply rewrite the rules to create additional bitcoin, the incentive to do exactly that would be enormous. The fact that this has not happened in seventeen years is not restraint. It is architecture.

Kratter addresses what would happen if a miner tried to increase the 21 million supply cap through their own modified software. That miner would find their blocks rejected by the entire honest network. They would have produced work that earns nothing and that no one accepts. Their chain would exist in isolation, attracting no users and no economic activity. The change would not take effect unless the overwhelming majority of node operators also chose to run the new software, which they have no incentive to do.

Alex Gladstein of the Human Rights Foundation describes Bitcoin as a “neutral and incorruptible” open standard. The incorruptibility is not a promise. It is a function of the architecture. The rules are enforced by a global network of independent nodes, and no single actor has the standing to override them.

The Hard Fork Test: Why Bitcoin’s Stability Is Proof

There is a useful diagnostic for whether a protocol is actually decentralized. A protocol that hard-forks^{A rule change that is not backward-compatible, so every participant must adopt new software or split onto a separate chain.} frequently can be a sign that a small group holds significant influence over its direction, since someone is deciding what the new rules will be.

Bitcoin has not changed its fundamental consensus parameters since Satoshi Nakamoto launched the network in 2009. Saifedean Ammous offers the clearest illustration of what this means in practice. The original Bitcoin software that Satoshi ran to start the network in 2009 would still synchronize with today’s blockchain, with one minor bug fix for an issue Satoshi was not aware of at the time. The consensus parameters are the same. The supply cap is the same. The rules that governed the genesis block govern every block being mined right now.

Most other digital currencies have hard-forked multiple times. Their development teams describe this as upgrading. What it actually demonstrates is that a small group can decide to change the rules and that the rest of the network will follow. That is a description of centralized control, regardless of how many nodes the protocol runs. The ability to change the rules is where the control resides.

Ammous makes the comparison directly. Facebook, Apple, and Amazon all upgrade constantly, because anything centralized is easy to change. The entity in control makes the decision and the system follows. Bitcoin’s inability to change quickly is not a weakness but evidence that no one is in a position to change it. That is what decentralization looks like from the inside.

The Real Risk Is Not Mining: It Is Custodial Capture

Aaron van Wirdum, author of The Genesis Book, identifies what he considers the genuine long-term threat to Bitcoin’s decentralization. It is not concentrated mining. It is what he calls the email problem.

Email is a technically decentralized protocol. Anyone can run their own email server. The infrastructure for independent operation exists and is accessible. In practice, the overwhelming majority of email flows through a small number of providers, mostly Gmail and Microsoft. The protocol remained open. The usage centralized around convenience. The result is a system that is technically distributed and practically concentrated, where a government order to those few providers reaches most of the world’s email.

Bitcoin faces an analogous risk. In principle the protocol is completely open. Anyone can run a full node on a standard computer, hold their own private keys^{A secret cryptographic number that proves the right to move bitcoin from an address. Whoever holds it controls the bitcoin.} and transact peer-to-peer without an intermediary. In practice, though, as Bitcoin has become more mainstream, most users keep their Bitcoin on exchanges and custodial services, where the service holds the keys and the user holds only a balance in someone else’s accounting system.

Van Wirdum’s argument is not that custodians are inherently illegitimate. It is that if self-custody^{Holding your own private keys yourself, typically on a hardware wallet, so no third party can move or freeze your bitcoin.} and node operation cease to be realistic options for ordinary users, Bitcoin’s censorship resistance erodes regardless of how distributed the mining is. The 2022 Canadian trucker protests illustrated the point from the other direction. When the government invoked the Emergencies Act, every major financial institution complied with the order to freeze accounts within hours. One hundred percent of the centralized fiat donations were confiscated. Approximately 70% of the Bitcoin donations reached the recipients, not because Bitcoin is immune to government pressure, but because a decentralized network with no single point of control cannot be switched off by a single order. Source: Alex Gladstein, Human Rights Foundation

That outcome depended on the Bitcoin donations being held in self-custody. Had they been held on a Canadian exchange, the order would have reached them too.

This is the distinction that matters for anyone concerned about Bitcoin’s decentralization. Mining concentration is the wrong threat to watch. The right question is whether ordinary users retain the ability to hold their own keys, run their own nodes, and transact directly on the protocol. As long as that option exists, the network’s decentralized nature is preserved. The effort worth making is to keep that option not just technically available but practically accessible.

This article is part of the Bitcoin Myths series. To explore the full Bitcoin Myths series, start with the hub page where all 20 myths are mapped and linked.

Everything on this site is for educational purposes only. It is not financial, investment, tax, or legal advice. Bitcoin carries real risk. Prices move. Do your own research, think for yourself, and speak with a qualified professional before acting on anything you read here.