Your thorough examination really does show here. I have, in the past, been for the legalization of all drugs. However, assertion 4 from your points has made me reconsider. If your assertion is true (as far as "permanently alter the user's personality whether they are using or not in a way that is provably dangerous to the public"), then I may end up changing my mind.
However, let me offer this anecdote: A couple that are very close to me ended up becoming addicted to Meth. The guy was very charming and had a very good job where he was fast working his way up. The gal was an RN. They had a nice middle class house.
Eventually, he lost his job and started to manufacture and sell the drug. He became what most would call a dangerous criminal. There were guns and supposedly some violence, though I do not know the details on this, as I had been dissassociating from them. Even from a distance, the things I was hearing scared me. Well, finally he was arrested and charged with several things, I don't recall what all. He went to prison and his gal was rumored to have taken over the business.
When the police came for her, the neighbors all stood out on their front lawns in their nice cul-de-sac and cheered. However, the police had entered her home without probable cause, without a warrant and without her permission. So, it ended up that no charge they could bring against her would stick.
Fortunately (or unfortunately from another perspective) her daughter's juvenile dilinquency (big suprise there, eh?) made it possible for a judge to require the mother to undergo drug testing, and the judge then ordered inpatient rehab. This was possible under a state law that gives a juvenile judge certain powers over the adult responsible for a dilinquent minor.
Amazingly, the rehab worked. Meanwhile the boyfriend, now in prison, was also involved in "Recovery".
It has now been many years since his release. He is very successful as a high level manager in his career. She has regained her nursing license and another advanced degree in nursing, and is well respected wherever she works. They were both extremely addicted to Meth. If you met them, they would appear to you in every way as if they were always the way they are now. Nearly everyone likes them.
I am telling this story partly in contemplation in considering your claim that Meth causes irreversible damage to the personalities of people which causes those people to be permanently dangerous to society. Are there studies which back this up? Perhaps you have an anecdote which contradicts this one I have told. Or did you mean to say that these people are a danger as long as the addictive behavior is active?