So what? There are also goals like having no workplace related deaths / injuries. Considering what is possible and not is not required for setting goals and can lead to a closed minded approach.
If you are willing to spend $80K per year on each drug user to keep them in jail, why are you unwilling to spend a fraction that amount of money on helping them kick their addiction?
Think of it as an investment. If we can save a bloodline from being corrupted by drugs it can have a big upside if you include all of the productive goods and service the dependents may generate. It can also result in improved safety in public which has exponential effects in being able to use that area in the real world.
>why are you unwilling to spend a fraction that amount of money on helping them kick their addiction?
Considering there is no drugs in prison they will be forced to kick their addiction.
Also there definitely are drugs in prison, they get flown in, smuggled in, and even guards have been known to supply them. Their value is 10x higher in prisons because prisoners are super bored and got nothing better to do.