I think deeply inside everyone is one. We are narcissistic to our self, needs and skills sometimes when we are not aware and sensitive about other people. I won't deny I am one. 

Then again, is it wrong? They are just being true to themselves and their feelings. People tend to call show-offs poser also.

 Do know that if you mock someone else poser, it probably signifies problems with you instead, not the person you accused. Why? In the first place, his/ her show-off is not meant for you. Thus, you cannot blame someone else if you cannot relate to their way of expressing themselves.

Get a gang to mock him/her again but why waste your time?

Don't you have your own life to live?

Congratulations, You have just found the hater in you.

It is a good progress because the Step 1 of healing process is to identify the problem, before seeking cures.