Too many times people are not as mature as they think they are. They think they learn to be adults, but what they actually learn is how to camouflage their narcissism better.
Which is why if you are in a group of 15 year-old-girls and you haven't learned reaction formation, you will get called arrogant. In reality, your narcissism and theirs are just about the same amount. They move on to be moralizers while you stay in the rawest form. But one way is more socially acceptable than the other, because the culture is doomed.