Uh, yes, you can steal. Just because the vault is open at a bank doesn't mean that you can walk in, take the money and leave, and then claim that it's yours bec

Uh, yes, you can steal. Just because the vault is open at a bank doesn't mean that you can walk in, take the money and leave, and then claim that it's yours because they didn't lock the door. When you send money to an exchange, there's an understanding that the money now belongs to the exchange. The exchange waits 6 confirmations to ensure that the money is not easily stolen, but the money legally belongs to the exchange as soon as the transaction is sent. --------------- Also, a 51% attack doesn't give you control over the cryptocurrency. You still have to follow the rules of the system, you can't print extra money from thin air, you can't spend money you don't control, the most you can do is change the ordering of the transactions that have happened on the system. And a lot of times, those transactions have block height or block id dependencies, which means you are even limited in your power to do that. A 51% attacker is not God. They have a limited set of actions they can take, and while certain forms of stealing are included in that set of actions, it's overall a pretty limited set of things that you can do.