This article is very high level, but I have been giving this some thought. Some aspects of masculinity can be toxic to the people around the man, but those aspects also tend to be something that was once (and no longer is) evolutionarily preferable. An example might be a man who has casual sex with lots of women. If there is one thing those men tend not to do, it's reproduce successfully. This is pretty ironic, because through most of history this may have been a singular factor affecting the extend of one's reproductive success. Toxic masculinity then might be something that used to have reproductive utility, doesn't anymore, but is perpetuated mainly by men and for men. It's mostly men that are impressed by hookups that other men have. No one is nearly as "impressed" when you actually have a child and raise them to be successful, which is strange, because that is the essence of reproductive. Whatever men do that is good for reproduction in our actual environment (make big bucks in tech being an example of something that has no precedent in evolution) could be considered masculine. Whatever men do, to impress other men, that is harmful to the people around them and yet not useful for reproduction (lots of casual sex while using birth control) could be considered toxic (?). Otherwise, no, whatever works isn't toxic.