They lack the tools that gives them the ability to do so.
It's like telling a man to go fish when he's never touched a fishing rod in his life and lives nowhere near a body of water. Some men learn from their fathers. Some learn from homies. Some learn from their mentors. Some learn from the Internet. Some learn through trial and error. And some never learn at all.
Thing is. You have to love yourself. And if you don't, you need to get on the road to getting there. You might have to sit this one out for a while, and that's okay. Don't worry about people who laugh at you because you get no buns, for those are the men and women who put value in the wrong things. They will be the very same ones who'll wind up depressed and struggling when the well dries up.
An egotistical man's worst fear is failure; a truly confident man's worst fear is giving up. Cause if you fail, you just get back up. But if you give up, then that's it. You lose. But don't do it for the girls in the tight dresses and the hazy Instagram filters, do it for yourself.