I've known a bunch of addicts - including my dad, although he quit when I was still very short, so I mainly only ever saw long-term aftereffects with him - but I've personally just never seen any point in it or any reason to do it. Alcohol, tobacco, marijuana, LSD, whatever. It's just useless pointless crap to me. It took me a long time to understand fully that it was a 'real' thing that people struggled with. I feel lucky (and kinda guilty sometimes) when I see how hard other people have to fight to *not* do these things. I've seen the struggle since long before I even realized what it was, I've learned the patterns, I know how the rationalization works... but I've just never been there. I guess I feel sort of like when I walk into Costco and see a row of TV sets priced over $1200. People CARE that much about television? Seriously?
I grew up in a place where marijuana was easily available. Where it was, literally, a weed. Pretty much any kid could take a walk down any creekbank on any Thursday afternoon in summer, and find a patch of it - none of it cultivated, or hidden, or anything, we just lived where it grew wild. In places people passing through just literally pulled their cars over and cut fifty pounds of the stuff growing in the ditch whenever they felt like it. It was free for the taking. And so in my school there were a large number of people whose brains did in fact, yes, turn to mulch over the course of years of frequent, heavy, use. Don't let people tell you marijuana has no long term effects - kids who smoked a pound of it a month for years starting at age twelve, reached mid high school with no functioning brains.
And all of that which I saw playing out around me at school - were to me just another case of boring stupid people doing boring stupid things.
Except sometimes when the 'heads would do something exceptionally pathetically stupid, and then ... it's insensitive as hell, but I was, like thirteen at the time and didn't care about the boring people anyway ... I considered that kind of stuff just hilarious. I stopped short of mocking them openly, but that was mostly because they were stupid boring people and I didn't care enough about them even to mock them.
Now I'm a grownup, and I see that sort of thing for tragedy of a pathetic sort - but I just couldn't have handled that much tragedy when I was a kid, so it was all just a big stupid joke played on stupid people.