Whether or not it may be true isn't really the point. It's more that being confident if a byproduct of success in whatever you're doing. If you're very good at something, you will be confident when you do it. As a guy, you won't be confident with women if you're rejected a lot. The guys who are confident are that way because they don't get rejected a lot.

Hence the "confident guys" are usually the tall good looking ones who do exceptionally well with the super attractive girls. Then the guys who are not as confident are generally rejected by most, but then told to be confident anyway? Never made sense to me.

If I'm bad at basketball, why would I be confident when I play?