in a nutshell: because we need the practice.
we're not being eaten by bigger animals with bigger teeth anymore. if we didn't fight each other, we'd have nothing to make us improve our ability to kill and defend ourselves.
we'll need that ability one day to fight for the existence of the human race, when we do come into contact with something that can eat us in the future. remember, it's the threat of death that drives evolution. paradoxically, life couldn't exist if things didn't kill each other. so, what we're really doing when we're fighting amongst ourselves is sharpening our claws, training to become better at war.
we're not being eaten by bigger animals with bigger teeth anymore. if we didn't fight each other, we'd have nothing to make us improve our ability to kill and defend ourselves.
we'll need that ability one day to fight for the existence of the human race, when we do come into contact with something that can eat us in the future. remember, it's the threat of death that drives evolution. paradoxically, life couldn't exist if things didn't kill each other. so, what we're really doing when we're fighting amongst ourselves is sharpening our claws, training to become better at war.