Researchers who share the same idea as Sigmund Freud regarding aggression believe that it is a basic human instinct.
Every human in the world will feel aggression at some point of their lives - when you are angry at somebody, when you can't learn a boring lesson, when you can't beat the main boss in a game. According to Freud, this feeling of aggression is inborn, and it is one of the most basic instincts we feel.