Why do so many men willingly remain in the Friend Zone?

Do they not realize what a woman has told them is, "You're OK and all, but you're definitely not dating material. The thought of sex with you makes me want to vomit. One day some woman who is less attractive and with less options than me will have to settle for a guy like you. But, you're reasonably smart and funny and want you there to boost my ego when the latest hot guy I met at the bar cheats on me."