Anonymity is the reason. I think the worst of mankind rears its face when they have no fear of repercussion.

You begin to realise the true extent of human depression when you look on twitter or youtube. There are countless people saying the most heinous things, like threatening death and rape. I tend to think about how sad their life must be. The idea that they hate themselves and the world so much that they have to find an anonymous outlet to spread hate and vitriol in order to make others feel how they feel What a sad world we do live in.

Youtube doesnt police the racists...better to let the blow out their steam on youtube then shame them later if they get famous or get some kind of success.