I've seen functional heroin users.
I haven't. As an example, I never really did pursue my field of education. For whatever reason, I just lost interest in terms of actually working in that same field. The field I ended up working paid well over a hundred thousand dollars a year. Travel was basically all year round at the finest of retreats and hotels, the best available cars, most times bought on the spot, like you're driving by a dealership and somebody says, hey, turn around, I want that car. Nice homes, etc. Any additional expenses were all per diem. I'm talking just a lot of money was made and boy did we have fun constantly.
Anyway. A lot of really good men died getting involved with that stuff. Guys who had everything. Good people. I never knew how they came to get messed up in it, we always kept rather guarded circles, mainly because there was so much money being passed around.
So, after a few days of relaxation, getting ready to head out on another trip, someone wouldn't show up, ended up they were found dead in a hotel room some place, left there by whichever skeezers they were with the previous night. I'd need both hands to count how many times that would happen, whther it was coke, heroin or whatever else it was.
I dunno. Maybe some people can stay functional for a while, but it always gets them in the end if they don't get help they need, or if nobody who has the means and will to help them knows about it.
