The logic is it also ruins other peoples lives. No one exists in society in a nut shell or as an island. If your choice to use drugs would expose, entice, or otherwise encourage a person to use drugs then it is reasonable in my opinion for the state to protect people from it.

That being said clearly our approach isn't working. There shouldn't be laissez-faire drug use all over but there shouldn't be life in prison immediately consequences either.

The most succesful drug rehabilitation programs are mandatory rehab facilities that are a choice alternate to going to jail for an equal amount of time.

Also housing first models are incredibly effective. But... the entire western world uses housing as an investment vehicle and commodity so it is diametrically opposed to housing first initiatives. If the average citizen is paying 50% of their income for housing and then "junkies" get given free housing the political party that implemented it would be booted so fast.