Human beings, like all other animals, frequently compete with each other for resources and access to better mating. As it happens, in our particular species it is the male who has evolved the lion's share of the aggressive nature required to obtain and protect these things in the course of daily business.

More aggressive individuals dominate and control; less aggressive aka passive individuals are dominated and thus controlled.

Therefore, survival success in pre-modern times depended greatly on aggression, whether on an individual, familial, or societal level. That's still true today, despite the fact that we have in most cases created societies with laws and other means to enact fairness, which in theory should (but does not) render aggression and the associated power struggles obsolete.

It's good for a football team to be aggressive. When in pursuit of a goal aggression is desirable.
I think what you're asking about is social aggression and violence. This type of aggression comes from anger and frustration.
When people feel frustrated in their lives, anger is a natural result and that will lead to aggression and violence.
When people feel that their lives are meaningful, that their concerns are being heard and taken seriously, aggression lowers.

Aggression may have a chemical ,hormonal,or genetic basis.Aggression is also a way to maintain social order in many species . So in reality an individuals degree of aggression is a combination of his genetics , environment and culture.

There must be over a million causes of aggression out there.
Whether they're justified or not, is a different story.