Having strong and true conviction and sticking to it can be rewarding. -- I'm not sure if that's called confidence and/or narcissism to some extent.
Classic Narcissism includes delusions of grandeur. I believe that this can manifest itself as "I'm right and I'll hold this position until I destroy myself". The narcissistic personailty is drawn to trading.
Takes a bit of narcissism to believe you can beat the market professionals at there own game doesn't it? take food out there mouths? on the other hand, maybe you guys are professionals??
Another manifestation of the delusion of grandeur aspect of narcissism, shows itself in the posting of events (trades) designed to prop oneself up in the eyes of others. In addition, these types of individuals will attempt to get the most recognition from others by making outlandish claims that will be crafted, sometimes with intentionally erroneous "facts", in order to generate dissension with and attention to, themselves.
I think trading is the reverse of narcissism-the market will kick your butt and make you look silly- a narcissus would not risk that. I've been a narcissistic rock muso and life beat that out of me.
You are correct that narcissism and successful trading are at polar opposites, however your statement about risk is incorrect. Narcissists take huge risks and that is one of the major reasons that they are not suited to trading.