A few things. Sometimes I will echo what someone else has said.
First, everyone has his own reasons for going on T or not going on T. If hair loss is the main reason someone doesn't want to go on T, then that's his reason. It's not our place to judge.
Second, as someone else pointed out, you can take T for six or eight months, get the vocal changes, and then stop. Some guys do this. My therapist counseled a guy who did this and is apparently very happy that way.
Third, as a few people have pointed out, just about every trans man will get changes to head hair and will have a male hairline after a while. This is not the same as hair loss or balding. I don't think I know a single trans guy IRL that this hasn't happened to.
(Oh, stop with the numbers.) I know a BUNCH of trans guys IRL, and a few have experienced true hair loss and look fine--they're just regular guys. Only one guy has really lost a huge amount of hair. So saying that most trans guys go bald seems like a gross overgeneralization based on what I've seen in person and heard on Susan's. Unless you want to jump forward in time and predict that when we're seventy, we'll all have thinning or nonexistent head hair. I have no opinion on that because I don't know any seventy-year-old trans men.
I wasn't sure whether my own hair changes were hairline shifts alone or incipient balding, so I started taking Finasteride. I stopped about five weeks ago, and I can definitely say that it was helping to at least slow down the loss. I could go back on it, but I'm more worried about my hematocrit at the moment. We'll see.
I started T at 46, I'm 49 now, and my hair still looks great. I did look in the mirror yesterday and think, "You know what? If I lose it, I lose it. I'm not going to stop T. And, you know, I look pretty damn good with this hairline." I like my current hairline, and so far my marginal hair loss seems to be mostly all over--no bald patches and no obvious thinning that I or anyone else has noticed. The only real difference is in the hairline. In fact, I have my father's hairline, my brother's hairline. I actually like that. I'm also getting used to the idea of losing my hair, period, because, for me, T is necessary--and because I look like my male relatives. (Plus, my therapist has commented that my hairline looks really good, and he just corroborates what I think myself.)
Thus endeth my peroration on my personal observations and experiences with T and hair loss.
If T isn't for you, even for a short period of time, then more power to you. It's always there if you change your mind.