Many drug addicts don't want to be addicted, and would try to go through treatment if provided. But some are inveterate, and don't want to quit. What do you do with them?
And, to be quite blunt: If someone wants to be a meth-head, there's plenty of ways to consume it that don't create hazards for other people.
Edit: I think it's perfectly acceptable, in guaranteed housing situations, to say "If you create a hazard you will go to jail."
You skipped a step or two in there, but I will note that if you had real health care, the homeless adhd and such would be on their vyvanse prescriptions rather than self-medicating with meth.
First, the general stupidity: I didn't assert a single thing you claimed I did.
However, there's a reason stimulant medications are monitored by a doctor: escalating dosages due to normal tolerance needs to be distinguished from escalating dosages due to use and abuse of the medication for (initially) spurts of productivity and (eventually) avoiding the need to sleep. I can assure you that you can stay up 4 days on Vyvanse™ (i.e., fancy amphetamine) just as easily as you can on methamphetamine; the difference is the doctor and pharmacist keeping you to a sane dose, even if everyone involved is winking and nudging about whether you actually have adhd.
Imagine if addicts got a limited amount of their fix for pennies with very basic oversight, instead of screwing around with random chemicals that seem to make life bearable for a short period, but which quickly result in escalating dosages, health impacts and antisocial and criminal behaviour ultimately resulting in homelessness and incarceration with all of the social and economic costs involved in that.
You seem unwilling to say what you actually want to say. I'm more than happy to dance around it if you are.
Drug addiction and mental illness is another story.
In which case you're essentially saying "meth users decide everyone's housing status".
I'm saying reaching the state of "no homelessness" is dependent upon finding something to do with the worst of the homeless.
For a tech analogy, imagine you've architected a system that has 99.5% uptime. You might be able to imagine a way to get to 99.9% up time.
With enough resources, you might even be able to get to 99.99% uptime. With laser focus and a giant dedicated team and an immense budget, maybe you can get it to 99.995%.
But what would you do if some exec came in and said we need 100% uptime, and we are a failure as a company unless we reach that?