I have a muscle-wasting disorder (Spinal Muscular Atrophy type 3) with no treatment or cure. My drug use started as a coping mechanism, then turned into a crutch. Due to irresponsible drug use, I wasted my physical prime (17-21) chasing cheap women and the next high.
I now live a solitary life, with my parents, who are slowly passing the reigns on to me as they get older. I've finally reached a stable point in my life (at 27,) but because of my disorder, don't get out much, am in constant physical pain, and am losing more and more control of my body by the month. In the last year I've made a full transition to using a wheelchair outside of the house, conveniently broke my ankle right after I got the chair, and gave up on dating.
The reason that I use drugs now, is that I just fucking love them. More than money, more than possessions, more than 99.9% of human beings. I have no illusion that anyone will ever want to marry and procreate with someone in my physical and financial state, so I dedicate my time to my work (writing, music, graphic arts,) and my Self to expanding my consciousness.
I stay away from the addictive stuff though, especially painkillers, because I would never be able to quit (my physical pain is only going to get worse, so I made the choice to live with it rather than fall into opiate addiction.) I'll grab some poppy seeds once a year, and binge NO2 during a trip every few months, but I keep my average usage of all drugs down to 1-2 times a week.