That's crazy talk, man.
I've played tons of bad guys in video games. The number of people I've killed IRL: 0. On games I've demanded more cash for jobs, lied, cheated, stolen, murdered. IRL I've only been in jail once, over a decade ago, for driving without a license. IRL, my friends and family all consider me to be a nice guy, who will help out when I can, even if I am a bit of an asshole.
There have been a few choices that have made me squeamish over the years of gaming when playing an Evil character, but I've made em for the sake of the game and the story. That's because that's all it is, a game and a story. Even in PvP, no one's really getting hurt, aside from maybe some bruised egos. To generalize like that? That's like saying every actor that's played a movie villain must be evil. Bruno Ganz, who played Hitler in a badass movie called Downfall, would certainly not want to exterminate Jews outside of the role. It's madness, that line of thinking.