Answer:
Well, when someone bullies another first of all it is just plain mean. But it also hurts the person being bulled and lowers their self esteem.
Bullies themselves are bullied, and they want a way to vent their anger, even if it means hurting someone else, because they ether don't care about who they are hurting, or don't realize they are being hurtful.
Bulling is a serious problem today. And it is of course problematic.