
It’s a fairly specific situation/kind of person the guy is describing here. A highly insecure man hasn’t fully developed his own inner confidence or moral core yet, so is more vulnerable to ill-intentioned advice or stereotypes about what a man should be. So when he’s trying to prove he’s not weak, he may go down a bad path and do extreme things to prove himself. Note that “trying to prove he’s not weak” is VERY different from “actually becoming stronger”.
The problem is NOT that a man is insecure and working on himself. Wanting to become better at something, become a better person, strengthen yourself physically or mentally, etc. are usually a good thing. But then there’s not really a need to “prove” anything, because as you get stronger at something, you know you are stronger at it, and you get more secure, and other people’s opinions on it don’t matter quite as much anymore.
Maybe I’m misunderstanding, but I don’t agree.. I think the very definition of being secure as a person is that you know which criticism is valid/helpful for you to improve as a person, and which criticism is just jealousy and not worth dwelling on (even if it stings temporarily).