> when they rolled back the entire ethereum blockchain The Ethereum did a dick move but there was no rollback of the chain. None. Zero. What happened is that

> when they rolled back the entire ethereum blockchain The Ethereum did a dick move but there was no rollback of the chain. None. Zero. What happened is that the ETHs from the DAO hacks were locked for a few weeks (months?) in a smart contract, even after the hack. The (dark side) hacker couldn't get them immediately. So kid Vitalik quickly changed the code and pushed a new versions in which the rules of the game were modified, preventing the unlocking of the stolen ETHs. But at no point was a single transaction rolled back.