Yes, it was the narcissism that struck me when I read his book. If memory serves, it is almost as though he was paying homage to himself. Even in the video in this thread, some of his humility is couched in humblebrag.
To be fair, his nature has served him well for a time and he has made more money in his life than I ever will. But his disrespect for risk was also the seed of his destruction. His need for attention and to stand out and be different (exhibit one: the look-at-me pastel-colored clothes) could possibly explain his propensity to doggedly trade against a prevailing trend. He may have espoused testing everything that could be tested, but an inflated ego evidently made him that much more vulnerable to confirmation bias. So, depending on the level of ego, even an otherwise smart guy can convince himself to do stupid stuff and blame a previous blow-up on an anomaly.
So just as the difference between medicine and poison can be in the dosage, confidence is a good thing but hubris kills.
I suppose it's easy being an armchair quarterback/psychologist. If it were difficult, I wouldn't have posted.