Uhh, not for the coins themselves but certainly for the goods that were exchanged with them? I mean if you did this IRL, the party providing the goods would ju

Uhh, not for the coins themselves but certainly for the goods that were exchanged with them? I mean if you did this IRL, the party providing the goods would just report them as stolen and the traditional legal system can be used to retrieve them. Have fun arguing in court that a 51% attack somehow means you get to keep the thing. This is no different from paying for the thing and stealing the money back IRL. The only thing crypto allows you to do is to distance yourself _physically_ (i.e. you don't actually have to break in and steal money), it means f*ck all _legally_. A similar existing situation analogous for 51% attacks is "paying for something with a personal check and later having it bounce". In fact all major breaches of crypto today involve stealing the coins themselves, which as commenters below have mentioned, cannot be done with a 51% attack---you still don't have the private keys.