Above all other things, BTC is an autonomous zero trust system: You don't trust that something else is right, you verify it. (you might argue that the software

Above all other things, BTC is an autonomous zero trust system: You don't trust that something else is right, you verify it. (you might argue that the software is trusted: but you can verify that too, if you have the interest and resources) Practically everything that Bitcoin does is a pure mathematical function. So long as everyone applies the same rules they will also come to the same conclusion about what the state of the system is— autonomy and consensus are not incompatible. Unfortunately, there is _one_ thing that can't be decided autonomously with consensus in a distributed environment of mutual distrust: Transaction ordering. There are a bunch of superficial reasons why this must be so, but it can also be understood from the perspective of relativity: The apparent order of events depends on your frame of reference. Without a single privileged point of observation ordering can be ambiguous. Ordering is important because the order decides which of any repeated spends of a coin is the correct one. Bitcoin uses a special kind of election to decide ordering, since consensus order cannot be achieved autonomously like everything else. Instead of voting by number of people or by number of computers— which is easily compromised by sibyl attackers— it votes using energy: The network selects the history that has the most sum-total energy spent crunching on it. Because the energy is spent confirming the whole of the history, going back and reordering old parts becomes very costly the further back you go... and participants who don't go along with such an effort have an inherent advantage, since they're not losing the sum total of work after that point. And even then— all they can do is reorder the history, they couldn't reassign coins without having ever owned them. The people spending energy to validate transactions have their rational incentives largely aligned with the rest of the system by virtue of the fact that if they spend energy on a losing version of history, that energy is lost forever and any income they would receive from subsidy (the initial minting of coins) or transaction fees is lost forever. Their income is generally maximized by mining on the single chain with the best odds of surviving, and this makes the system converge. So could some quorum of Bitcoin users seize back the coins? If by quorum you mean all surviving users after the change, yes: If all the users want to change the software can be rewritten arbitrarily. But it would sort of moot the system if they did. Could a simple majority do it? No way. Bitcoin isn't that kind of consensus.