Okay, to be very honest...
Growing up throughout high school, I let people walk all over me. I didn't exacty feel victimized, I just didn't care. I didn't care about anything. Once I realized how bad that was, I started sticking up for myself in all sorts of ways. I realized I have many strengths--some which I didn't know of and others that I completely ignored. I guess as a compensational thing, I began exploiting my strengths, speaking of them proudly, juicing them to prove to myself and others where I stand. Basically I became a cocky fucking asshole. The worst part is that having people reassure me that I was cocky just made things worse because it just made me cockier. I felt invincible, I had the craziest superiorty complex ever (I didn't realize how bad it was though). Finally a girl criticized me with a below-the-belt blow (literally), I'm sure you guys can guess what she might of said...suddenly I realized that I don't have the "cock" to be "cocky". This basically shattered my ego and I've started from scratch since (which I'm very happy about, since I learned being an asshole gets you nowhere).
This was my specific issue though. I felt above average in many things about myself except my penis. Before this happened, I was aware that I wasn't the biggest out there but I didn't care anyway because I didn't give it a second thought. This can happen to anyone with anything. One might have a large penis and be particularly proud about it until his girl rants about how he completely sucks in the sack. I'm sure he'd feel the same way I do (or did).
So yeah basically, indifference/meekness--->insane superiority complex-->inferiority complex on this specific topic. I'm trying to change this though, I know I can but it just hasn't happened yet.
I feel extremely embarassed for spilling my guts like this but I really don't care anymore. The best advice I can give anyone about this is that being cocky NEVER gets you anywhere. There is NO ONE who's built in a way that can please all, therefore NO ONE should act that way, even if just for kicks. It doesn't pan out in the end. I'm sure some of you are reading this and think I'm pretty fucking dumb for ever dabbling with narcissism, which I am, but you don't really realize how deep you're in until something like this happens. I just hope anyone who can relate will take what I said into account and steer away from that dark dead end.