I think the metaphor is bad, but applicable in some cases. I remember a video (I won't link to it) in which a guy was arrested after a shoot-out with the police. In the police station the security camera shows him sitting alone at a table. He pulls out a gun from his baggy pants and shoots himself. That is really, really similar to a game-style ragequit. I don't think the guy was a typical depression case. He was cornered, screwed bad forever, and pressed "quit".