Its harm potential is somewhere in between. To put it in perspective, alcohol is worse than heroin. And like alcohol addicts, your friends should be able to get a clean and safe source to reduce damage, and the help they need without any fear of persecution.
You can't criminalize problems away. It evidently didn't help your friends.
I had a year or so that I had realistic mundane dreams. Just doing my chores, which I then had to do again when I woke up. Worse than any nightmare.