You're trying to use humans as an example for the possible disposition and psychology of aliens? Really?
Does it not strike you inappropriate to do so considering the billions of years of evolution and absolutely random events like mass extinctions that led to the rise of mammals and eventually humans?
Humans are the only real evidence we have of how a technological society develops. Evolution produced us, and evolution arises from the physical laws of the universe. Why should we believe it would operate differently elsewhere in the universe?
No planet will have infinite resources, so it's logical that life will develop through continuous competition for territory and materials--just like it did here.
Looking back at Earth's history, it's not like we are the only violent forms of life we know of. Quite the opposite.
Does it not strike you inappropriate to do so considering the billions of years of evolution and absolutely random events like mass extinctions that led to the rise of mammals and eventually humans?