Sometimes their insecurities are insurmountable. I absolutely do not carry myself in a way that repels or disgusts.
"She likes me so much that she wants nothing to do with me" sounds completely deluded, and if I say that phrase to myself, it makes me laugh at what a toolbag I sound like. (Though when women are extremely insecure, there's some truth to that phrase, as lame as it sounds).
So why do women, especially when they're beautiful, feel like they're not good enough for a really nice, authentic, interesting guy? I got my own flaws, struggles and insecurities, so it's not like I'm perfect or anything.