Haven't played video games for some time, but at least when I was still pirating, malware and spyware was pretty common. Bugs and incompatibilities caused by pirating were also not unheard of.

Playing pirated game is putting trust into the hands of some anonymous hackers. And that begs the question, what do they gain from giving out the game for free?

They could be doing it just for fun, for coolness, or out of altruism. And that's true for probably many case. But to say none of them wanted to earn expedient money would not persuade me.