Bullying is one of the largest problems in the world, and it will continue to be a problem for all of civilization as long as we have free will. This problem will never go away, but a lot of incidents can be prevented. The easiest way to allow a problem to continue is to be passive. When they bully can do things without consequence, that is when they start power tripping.
The key thing that links all bullying incidents is the perceived strength of the bully over the victim. The bully will get off on picking on those who they feel cannot retaliate properly or will not retaliate. People learn at a young age about the consequence system, and not having consequences will encourage their behavior.