Should I trust this well-known hair restoration doctor's advice?

Recently, I've been curious about hair loss, for a couple of years I've had a very tiny recession but still have a full head of hair throughout. I went to see this hair restoration doctor in NYC, well-known in the field and provided free consultation but I felt rushed through it, he put some device called the densitometer on me, a device that none of the dermatologists or other hair specialists knew about and said that I exhibited very early signs of genetic hair loss.I told him my father started losing hair and thinning at 46 (56 now) so he immediately prescribed Propecia, he rushed me through the whole consultation and I didnt really get my questions answered well (a lot of I dunno). The whole experience made me unsure whether if I should trust him and spend the $69/mo on Propecia for life if right now I have a full head of hair.I saw a derm and a trichologist and he thought it's not serious at the moment but if i start to exhibit signs then take it or take it to protect it.