Why didn't they just steal the $500k? They ended up stealing it anyway, BUT they risked it all on the fight. What choice would you make if you started with nothing: walk away with $500k or put up all of the recently acquired $500k on an even odds fight? Either way the bad guys will want to kill them.
shareI can't answer your question. But I have another question about the ending.
(Spoilers below).
Okay, they have double crossed these New York badasses that assure them they will be killed for doing it. Okay?
But no one is watching Harvey's apartment? He is hanging around, waiting for his killers to show up. They should be here any time Harvey says to Shawn after he comes in. So you figure someone is watching to make sure Harv doesn't leave.
Shawn says hey we've got a bag of cash for you. OK let's go. Off they drive in the girlfriend's old Pontiac station wagon. Happy ending!
But wait. Wouldn't someone have known about the girl? Or notice she's gone? Then find out what car she was driving?
I know it sounds like a lot of work, but these guys are supposed to be badasses. So, just because they took their time getting over to Harvey's place to kill him, they're just going to let them go, with all that money?