Is it true that people bully because they are insecure?

Why people bully depends on many factors, yes people often put down others to make themselves feel better because of this insecurity. Often people with a galaxy sized ego also can be the type to become a bully, because on the contrary to said person in the last scenario, they think they're better than everyone else. Bullies also put down others based on social status, income, or they just like seeing other people suffer. Some people might've been raised a certain way, never have been told no and when someone does they may resort to threats like in stereotypical school movies, And lastly, there's also people that simply just wanna see the world burn.