In the neighborhood where I had my apartment, I had seen cops waiting dow the block to arrest customers as they walked off after buying from two coke dealers, one was in a building my friends went to buy, another was right on the sidewalk, hanging out all day in the open (they paid some idiot to stash the stuff in his mailbox and would have him go fetch it as needed).
My friends used to hang around that sidewalk, but I started staying clear because I didn't want to chance getting arrested in a sweep.
These were hardcore users, and quite a few are dead now, some were homeless. Treatment would have been good, but fact is, that would not have stopped them.
One of them went to jail for robbing these two elderly brothers - one was always in a neckbrace and my freind and his pal were hitting them upside the head with a hammer, trying to get money from them in their home.
I had stopped his pal and another person from trying to break into an apt next to me prior to that one night.
Anyways, point of all that is it isn't just them using, it's assocated crimes and destroying their own health, and the impact on their families and friends as well.
I moved there in 1992, as the crack epidemic was beginning to wane, and seeing a women looking like she was in her late 60s when she was in her 30s selling her mouth for $5, it ain't cute.
Sad to say, but jail till they stopped would be the only way to stop them, and maybe even keep them alive in the long term. Maybe, as my robber friend stayed clean after coming out of prison got married, had a kid, but died earlier this year, but the wife wouldn't say why.