To be honest, I'm not sure if what the fansubbers are doing is legal. They're redistributing copyrighted material, as are the people who host it.
But charging for it, that's even more illegal, unless you've found a loophole in the system.
As far as hacking goes, it's just exploiting power. It's the same thrill people get when they steal, rape, or whatever. You're question is kinda like asking why powerful people become corrupt.