My cock size puts me in the top 2% other in length and girth. Very early in life I never gave it much thought. It is what it is. I thank my dad for his genetics which provided me with my endowment. I was a virgin until I was nearly 21. At that point in my life I had sex with a woman probably 8-10 years older. She made several comments about my size. I had also read the Kensey Report and Masters and Johnson so I was informed. I doubt that I have been over confident being thus endowed, just comfortable. Also comfortable with knowing that I was capable of sexually satisfying partners I was with. In my 40s I became involved with men. My reputation preceeded me. Word got around, thus creating a definite interest in what I possessed. Of course this added to my comfort zone. I do not think less of men who are smaller. I have only been with 3 who were larger.
I'm not sure its ego...but I think having a larger cock gives one more confidence. Like being seen naked in public or with a partner..if you're large there is usually less to be hesitant about rejection. Like if one is depanted in life...having the world see a large cock hanging there as opposed to a small one shrivled up...that just naturally brings about more confidence in life in my opinion. Its more rare to see a hung guy try to hide his cock than a smaller guy. Obviously this has nothing to do with performance in bed...but I think just in general it leans toward more confidence.