Adding my anecdote to this thread:
Started noticing hair loss in my early 20s but managed to convince myself that it was just stress. By my mid 20s when I was in a very low stress position I finally concluded that it was just plain MPB. I continued to ignore it for a while, just cutting my hair a little shorter than the longer hair that I wore before (usually more out of laziness than anything else). It finally came to a head a couple of months ago when I noticed that I had stopped turning the lights on when I went into the bathroom because I didn't want to see how thin my hair looked that day. That day I made an appointment with my doctor and got a prescription for Finasteride. Since I was very afraid of the sexual side effects of the drug, before I started I decided to shave my head to confirm my suspicions that I didn't like the shaved look. If I hated it, I'd start the medication and deal with the sides. Funny thing is, I really liked it. People don't treat me any differently than they did before which is what I was afraid of. Sure, women don't come up and hit on me but they never did when I had longer hair either so I consider it a wash. And I like it more and more now that I'm hitting the gym and adding muscle. Bald + muscular is a great look. Shaving my head (down to a #1 in my case) isn't my ideal situation but the way I see it, MPB is a better condition to have than many, many other genetic conditions.
If you're where I was a couple of months ago and your thinning hair is stressing you out, just give it a shot and shave your head. Best case, you like it like I do. Worst case, you hate it and you can see if fin would work for you.