There are 2 ways to look at bullying.

1. The bully as victim - The people who become bullies are in pain, have usually been bullied themselves by someone (often a parent), and are looking to get even for it by bullying someone else.

2. The bully as perpetrator - The people who engage in bullying are looking for a way to make themselves feel dominant and powerful by destroying someone's else's self-esteem. They get a charge out of humiliating other people. They enjoy inflicting humiliation.

Either viewpoint is valid, and both will often apply to the same bully.

I was mainly aware of the number 2 example when I got bullied a lot back in school. I became somewhat aware of the number 1 example after awhile too, but it didn't help much. ;-) I know of no sure way to stop bullies except to stand up to them when they try it.