Why is it not wise to get a hair transplant at 20 year old?

I keep seeing this pop up. I am 19 right now with a NW2.5-3 and just started taking finasteride. My plan is take fin for a year then — assuming I respond to finasteride normally (just maintain hair, am not a non-responder/super responder) — get a hair transplant at 20/21ish. Why would this be such a mistake? The finasteride should roughly maintain my hair for a decade or so, right? I’ll be able to live and experience a normal young man’s experience. Once it gets bad, I can just shave it once I’m older (which is not nearly as big of a deal), or I can get another procedure. Or hell, maybe there’ll finally be a cure for this shit disease by then lol. I just don’t get why it’s considered such a big mistake. I would honestly almost rather be bald than have these shitty temples, even if my density is still solid.

It is not wise to get a hair transplant at 20 years old because you can’t make a Personalized Master Plan as your future hair loss pattern doesn’t appear for most men until 25 years of age. Without a good plan, you start the transplant, use up the donor supply (which is limited) to deal with your short term problems and then when you keep losing hair you are out of luck as there is no more donor hair left. By then you might not just be bald, but freaky looking (nobody should look freaky). I have seen too many patient who did hair transplants at 19 or 20 and ended up regretting it.