I suspect the proof will present itself, if it hasn't already.
But let's throw another term out here: Hypothesis
Acting out our dark impulses, our Jungian shadows, in a "safe" environment, does not necessitate a person be a "bad person". In fact, it can be quite a healthy activity, as no one is actually being physically harmed. Of course, this does not preclude inflicting psychological harm, and this has been a well documented phenomenon of the internet, to the point of earning its own special terms Cyberbullying and Trolling. Does it happen here? There are more than a few threads that suggest it does. The "Hotel California" thread, countless Combat-Logging threads, equally countless "named and shamed" threads that have since been moderated into oblivion certainly support the position that this has and does happen here. I'd hasten to include a recent thread where the Original Post was praising their ability to menu-log out of combat situations as a reverse form of this.
So yes, there is evidence to support a position that there are people with inherent issues among us.