A) Culture matters
Apes have culture. Groups of the same species can have large hierarchies with lots of cruelty or low hierarchies with lots of love. You don't get to just dismiss it with an appeal to naturality like that. It to me seems clearly too pervasive as a factor for such acute lack of consideration.
B) The validation of our ego you speak of can just as much be love and kindness as it can be dominance or prestige, can it not? But you seem to merely focus on the latter, for some strange reason. Sure, humans got an ego and that ego is hungry. But there are many ways to feed and satisfy it. I have no idea why fighting for a place in a relatively adversary social hierarchy would be the "natural" way to feed it. But I'd agree that it naturally happens when thrown into such a hierarchy (since that is how it is the easiest to cope with it) and that this process has natural consequences. Such as cultural emphasize on narcissism and competition.
I also agree that this is not a new phenomena. Rather, it looks to me like a natural tendency of large societies. However, I agree with Hygro that we have reached new heights in that tendency. And as most natural tendencies, it can be fought, if so desired and kept in check. Or not.