A bully is rude, disrespectful, and hurtful, but bullies don't bully for no reason. They might bully because they are abused, bullied,or sad/mad.
Bullies don't want fights all the time. They are terrified on the inside. Bullies probably bully so that they don't get bullied. They don't want to be hurt. Bullies think it's better to be rude to people and they feel apparently satisfied.