In my understanding, and being myself among the "not manly enough", the one like us grow mostly in two kinds: those who mask masculinity well enough, and those who don't.

Yet all those who mask it are affraid of us because they could fail their masking around us. And they hate us because we found a way to make it without spending a lot of energy in masking. It is not something they know nor do willingly.

I have tried to mask, instinctively, and because society was waiting it from me. You probably tried too. It is far from easy and a constant pointless effort. It was rejecting our real self while seeking to make ourself accepted... And I think putting it like this makes obvious that those who success at masking need to reject us to keep up their mask: if they begin to accept us, it would be too difficult for them to reject their real selves hard enough.

Also, you may recognize genuinely masculine men at the fact they aren't scared by feminine men nor gay men around them.