I appreciate your breakdown. In other words, what you’re saying is that a man’s feeling of manliness is most often rooted in how closely he resembles societal expectations.

I think it’s pretty much the most reasonable explanation. But it still strikes me that men generally do not themselves think about it in those terms, and in fact consider it to be inherently emasculating. Masculinity viewed through this lens in essence becomes an act of submission to an outside force, which stands in contrast to many evident directives of masculinity such as independence and inherent drive.

Indeed the OP touches on this, implying that masculinity simply must be secured from within, with brazen disregard for the way others perceive you.

So if it does really come down to matching expectations, then it seems to be, as you said, frankly impossible