The more expensive their habit is, the more users will be tempted to steal. The strategy of keeping things expensive just leads to a crime wave. Better to switch to treatment for the hard stuff, and allowing people to self medicate with something safer. Keep non drug users safer on the streets that way. In the history of prohibition enforcement, the only time it was successful was when all fire was concentrated on those who sold to children. The criminals would police their own ranks to prevent anyone from selling to children, because they knew the heat involved with that. Once they switched to enforcing prohibition on adults, it led to a huge crime wave.
Alcohol prohibition in the US started out dramatically decreasing drinking for a short while. Then drinking started up again, this time with a huge crime wave involved. Criminals providing alcohol became big business.