What I've heard, although it was a really long time ago, is that trans men are twice as likely to go bald (compared to cis men) because of having two x chromosomes and that the gene for that is on x chromosomes.
But I'm not sure how much truth there is to that, if any at all. I don't think age has anything to do with it, some cis men start losing their hair young too. I know of a youtuber who started losing his hair when he was just 15, my best friend's father started losing his when he was around 20-25. Other men don't start losing theirs until they're much older, while many also of course never lose their hair. And I think the same about that also goes for trans men. So like if you have in store for you to lose your hair at age 30 if you had been amab or on testosterone, and then you start taking T at age 28, then of course you'll start losing your hair at 2 years on T.
As others have said, meds like finasteride and minoxidil can help treat/mitigate baldness. Those can be taken simultaneously as testosterone. As for a much more expensive alternative, hair transplants can be done as long as there's still enough hair on your head to move some of it to the bald area.
When I got on T I eventually got the male hairline, a very distinct M-shape, but no MPB. Only one of my male relatives got bald, my father's father. However my hair got very thinned out and brittle at around 3 years on T (which was 3 years ago) and kept getting worse. So after I had lost about 3/4 of my hair and it looked really bad and broken off (unintentional mullet that I could see my scalp through, around shoulderblade length at longest) I decided to just shave it all off. Not an easy decision to make as a newly detransitioning woman, but then I also don't know if it's really harder for one gender or the other to come to terms with baldness. Perhaps it depends more on the person.
It was relatively easy for me though, and I felt way better afterwards. Like relieved of a burden, almost. And I think I still look good. I still cried a bit at the hair salon when it all came off though. That was an intense moment. But only 2 weeks ago and now I'm totally fine with my bald head, although I miss the hair sometimes when look at old pics of myself. I maintain it by shaving it about twice a week. Upkeep is so simple it's totally the best thing about it. And not having to bother styling my hair or being bothered by getting random hair strands in my mouth, eyes, food, makeup, tickling me, clogging my drain, sticking on clothes, etc. It has many pros.
I have some wigs I can use whenever I want to, but right now I'm just really liking the bald look. I'm saying this because I used to be super scared of ever becoming bald, and get literal nightmares about it happening to me. I loved my hair really a lot, and I've always especially loved having long hair. I never liked it short, also when I saw myself as a binary man in my transition. When I got it shaved off, I was in the process of trying to grow it out very long and had been patiently saving it for 4 years. It was hard to come to terms with that it looked horrible and kept getting worse and thinner no matter how well I took care of it. That there was no point in saving even an inch of it.
I might try to save it out again once I've been off T a bit longer, just in case it was that which effed up my hair quality. But if not and if my hair never gets any better, I may just have to bite the bullet on that. My male hairline is the least of my hair issues, I think. If I can be fine as a woman with a beard and bald head, then dealing with the hairline becomes kind of a minor issue. I mean, keeping it bald is surely one way of dealing with it.
I get that the fear of losing one's hair is a real thing that many feel, and I've had that fear too. But actually facing it wasn't nearly as bad as I thought. It's actually not bad at all and I was surprised at how much I like it. I can totally make it work with my style and it sparked my creativity a lot. It became a positive thing for me, and improved my self esteem.
