I find it pretty laughable to make such a generalized, sweeping statement that men don’t care about their physical appearance. Pretty much every guy that I know puts a certain degree of effort into their appearance, whether it manifests itself in hair/beard grooming, hygiene, clothes, physique, etc. It seems far too reductive to me to conclude that men “don’t care” about hairloss just by pointing out the low percentage of men who actually seek treatment. People don’t seek treatment because they don’t work, or they don’t work nearly well enough to justify the cost at least or there are serious side effects that offer a real deterrent to doing so. That’s why there are so many bald guys who don’t seek treatment - they look at a dude like Lebron James, who is one of the wealthiest people in the country, try desperately to save what remaining hair he has - even in the face of ridicule - and he can’t even get good results. So what’s the hope/ point for us average joes?
As others have pointed out, a big part of this is just based on societal shifts. Dating and hook-up aps at the forefront of meeting the opposite sex operate under the assumption of mutual physical attraction. And obesity rates in the United States are higher among women than men, indicating that men are more socially conscious about keeping up a healthy appearance. I don’t think men accepting their fate and reaching for the razor can be explained by disinterest or neutrality, it’s the only psychologically viable outcome when a person comes to terms with the fact that their hair is gone and science can’t bring it back.
Maybe lots of years 
