Why do kids at school bully other kids?

The main reasons why kids bully other kids are:

• they are bullied themselves, either at home or school, and want to hide their troubles
• they are jealous of the victim or insecure about themselves
• they were raised in a rude nature in which they being a bully is natural to them
• they like the feel of control and power
• they have severe brain troubles (chemical imbalance, sociopathy, psychopathy, etc.) that causes them to be rude towards others
• they simply get a thrill out of bullying