My understanding of masculinity is that it is the characteristics by which other men rate a perceived level of attraction from females through which they determine a competitive standing. Men often think big muscles brings all the ladies to the yard, for example, so that is one possible display of masculinity, leaving “weaklings” to feel inadequate and of a lower standing.
My impression is that men generally believe showing off boners in public scares away the females, so it does not seem like a good candidate for being a display of masculinity. But if we assume that showing off boners is something men believe woos the women, is the aforementioned difference noticeable in practice? Science can reveal a lot of things that nobody would ever realize living out regular day-to-day life.
Not in and of itself.
If men believe that a big bank account attracts women, then one believing they have a larger bank account than another man may lead one to feel more masculine than the other (and vice versa). Of course, it depends on the culture. This may very well be the case in some cultures and not others.
Whether or not you share in my specific understanding, it is well documented that masculinity is cultural.
It’s all about perception, so what is actually true doesn’t matter. Certainly if one portrays themselves as having a high salary/net worth - e.g. driving expensive cars, wearing fancy watches, living in big houses – that may lead men to believe it. No doubt that is why men do exactly those things (at least in my culture).
Anything is possible. Again, perception, not reality. No one actually seeing your underwear doesn’t mean one isn’t thinking about the possibility of it being revealed. What if it slips out? What if you get into an accident and healthcare workers need to remove your pants to save you?
Having shinier peacock feathers doesn’t necessarily mean you are the more virile bird, but if that’s what you’ve got you are going to play it up to make other males think you are the one who will win the female’s attention.