There are few things more rewarding than watching people make fools of themselves on the internet, and what better way to do that than by completely losing it over a video game? Whether they go into a fit of hysterics or literally kill someone, we just can't get enough.
Besides, we've all got that one friend who takes games way too seriously. These people are worse. That's why they're on the internet. If one of these guys is your friend, watch your back next time you beat him at Halo.
And if you don't have a friend like this, well, maybe you should try recording your next game of Black Ops. Then post it on the internet, because chances are, you're a raging psychopath.