The drops I use to control my Glaucoma started out as a vanity drug to grow longer eyelashes, but they showed the side effect of lowering the pressure in the eyes. I hate the fact that I will have to use them daily for the rest of my life, but I really would rather do that than lose my sight. My lashes now make my wife jealous.
Finasteride/Propecia and Dutasteride/Avodart started out as medications to treat enlarged prostates. Hair regrowth sometimes was one side effect for men who took them. Personally, though, I have no desire to try to alter my body chemistry unless it is for a serious problem. While the prostate or arthritis might be on that level, hair loss never was nor will be.
Sadly, I have fear there always will be men who are so are scared and desperate enough about losing their hair that they will spend their money and risk screwing up their bodies in order to get their hair back. The pharmaceutical companies are more than happy to assist them in that endeavor.