My older sister died at 22 of a drug overdose, she had been taking drugs for half of her life by then, it wasn't because she liked drugs, it was to cop with a toxic, violent family. It was an unhealthy habit alright, she knew that, she even told me to never do drugs because it's shit, it was closer to compulsion and there was nothing the kid I was could have done.
There was a guy I knew who asked me to help him not smoke, to keep him from smoking at all cost, didn't take long before he decided to cut ties with me because I did. Haven't seen him in years.
These people were not stupid, unaware, or whatever, they knew deep inside they were hurting themselves, but they couldn't find a way out, and I know the answer was theirs to find and that all I coukd have told them would have just made them feel missunderstood, controled, stuff they didn't want because they had enough of it. They wanted to b treated like humans more than like problems to fix.
I too had to deal with self-destructive behavors, nothing as bad as above, but it gets on my nerves when people decide they know better and try to force me to follow their rules, all I want is to break free, break their will to "help" which makes a stubborn piece of shit. I hate those people because they make me hate myself more and it makes things worse when I hate myself.
It's no fun to be some crap in the gutter that some virtuous superior being tries to mold you into a proper person regarding their own standards. The answers lies within, not without.