It’s an evolutionary advantage. If our species periodically “thins the herd” by fighting wars then the weaker genes are eliminated from the pool and we become a stronger species. Competing species that do not do that are at risk of being wiped out by the ones that do. Passive, docile species have a tendency to get destroyed by more dominant ones. All it takes is one tribe to decide to be warlike before every other one has to either learn to fight wars just as well as they do or be wiped out.
Ah, spoken like a Nazi Theorist. That is pretty much my point.
Yes I understand we were forged in a brutal trial for survival. We must rise above the animal instinct.