Well there's a difference between recommending yourself for a job and running around telling everyone you're superior to them. The point isn't to think you're better than everyone, it's to try to advance your own interests, often at the expense of someone else who was trying to do the same thing or something incompatible with what I'm doing. Everybody acts in their own interest competitively and we're generally left with the more feasible solution, though maybe not our favorite one. Not always, though, which again opens up vulnerability to those plans. I don't even think you'd get past foraging societies without this sort of selfishness. You certainly wouldn't have civilization on the scale that we see it today. Not in human beings anyway. For that matter, though, I don't even know that a mobile species can survive without some degree of selfishness.