I've never seen any superstar in any field of competition lack confidence. It's that intangible that allows some players to take the 3 (basketball) at the buzzer and have the higher probability of hitting it. The skill to hit the 3 needs to be there for sure. But, we all have seen people who look good in practice and crumble under pressure. What increases the odds of hitting the 3 under pressure, skill sets being relatively equal? It is the psychological edge the best players possess. Confidence is one of the ingredients that provides psychological edge. One quotation I'll often repeat to maintain my psychological edge is "Don't be afraid of the moment" Jeff Van Gundy (former NBA coach).
And, confidence, to me, doesn't come from charts, methodology, or practice/repetition directly. It comes from the right kind of repetition. It comes from respecting your stops, respecting your methodology, following your rules over and over and over again. It comes from the self trust of knowing you'll do the right thing at the right moment. It comes from knowing that your healthy habits will give you your highest probability of executing under pressure. Self trust is something only you can give to you. Self trust comes from within. Confidence comes from within.* Without self trust, true confidence cannot be sustained.
* "Profitability comes from within." Todd Harrison