[Theory] I've always failed to see how "Narcissism" is negative

[Sassy Doll]

Post above me is good example of why you don’t want to be thought of as a narcissist

I understand that part, "don't brag too much because it could sound distasteful."

But Normans take it further and seem to say: "Don't ever think you are cool. You are always wrong and misguided."