If you say they are just self-destroying and "want to create suicide" and "don't want to help those who don't want help" then why not both not help AND not punish at the same time, and just let "nature" do it all? That is, you have elective suicide AND you say they have a free pass out of punishment (basically they can whinny out of public use without ANYTHING adverse), and because "life is misery" just you yourself endure the misery of living in a society where that dealing with the externalities of their highly public drug use as they die/don't "want to climb out" is just a part and parcel of YOUR life. Suffer a little by NOT punishing. You're already doing it, so just do more of it and screw your complaining.

Basically, that is, do everything you say while NOT punishing the public drug use and you just eating the social cost of that as part of life's natural consequences (or else, if you do criminalize it, make a criminal conviction for it both not affect the availability of rehab at all and make the conviction vanish entirely upon successful completion of the rehab and then eat and endure permanently the social consequences of THAT on the "life is misery by default" logic).