Most men are deeply insecure - even the ones who brag or otherwise act like they think well of themselves - because a patriarchal dominance hierarchy demands constant jousting for "rank" and the Act Like a Man Box demands constant performance of acceptable masculinity.

Women aren't spitting on, pouring drinks over, yelling at, or killing men who don't reciprocate their interest or help them get their way. People who don't know how to appropriately handle disappointment or rejection are acting like irrational children, not self-confident adults. Guys who actually are self-confident (and not just bluffing about that) don't rely on the external validation of random women and they don't need to "punish" them for refusing to validate them. Men who act like that are not self-confident in the least.