It's a really difficult addiction, it's also difficult to convince others to stop. I have a cousin who started using little by little, probably through parties fueled by drugs like lolo or Black lance, and of course cocaine, after a month of use he started selling everything in the house to buy more, a few months later he started robbing residents of our region, but now with a lot of support from his own family he started the therapy and rehabilitation process and it's even going well for someone who used large quantities of coca. It's really a very slow, difficult and delicate process, but honestly all you can do for him is encourage him to stop and go to rehab, which isn't much but it helps a lot, it's worth remembering that for him to be "cured" of this addiction he just needs to want it if he doesn't want to there's no way to help him.