I disagree. A lot of the reason a drug addiction is so devastating to someone's life is because the laws against them. People with lower incomes can end up homeless trying to get their fix because the (very cheap to produce) drugs have their price inflated by the laws (many a celebrity or high flying executive has been found to be a "functional addict"; able to afford their habit, but unable to seek help for fear of going to jail or destroying their career because of a criminal record). Someone with a drug addiction is treated as a criminal. Yes, I'm all for rehabilitative prison systems, but drug addicts don't belong in the prison system full stop. They have an illness they caught from doing something no more inherently morally wrong than drinking a beer or having an illicit love affair with a consenting partner.
Look at alcohol and tobacco; freely available drugs which it's very possible to become addicted to, (especially if you have some sort of metal illness or are part of a marginalised group in the former case). People with legal drug problems exist and sometimes they end up homeless, but at the same time, they can seek medical assistance, go to support groups and generally get help openly. Nobody's died while drunk because they were afraid of going to jail instead of getting medical attention (aside from cases when they were drink driving, of course; but at that point they'd already committed a crime aside from drinking the alcohol), misbehaviour caused by it is readily detected and if the product's got toxic impurities? The vendors and manufacturers are accountable (rather than sneering "what're you gonna do? call the police!)! Nobody's gone to jail because they tried to find help to quit cigarettes or alcohol. Nobody would consider banning alcohol. Restricting it, yes. But arresting someone for consuming it (as is the norm in many middle Eastern countries) would be unthinkable.
When Western societies tried to ban it nevertheless (from the influence of groups who considered such vices inherently immoral), what forced them to backtrack? People getting addicted anyway, addicts treated as criminals and being bankrupted by the increased prices cooked up by organised crime and police refusing to distinguish between AA meetings and speakeasys. The same problems we have with "illegal" drugs.
Arguing that addicts are inherently breaking the law by being addicted follows the same line of thinking as "hang suicide survivors for attempted murder".
Related note: Your reasoning is called Broken Window Theory (i.e. "if you allow errant behaviour, it leads to more and more crime"). It's beloved by law enforcement (because it gives them something they can do; crack down on petty crimes and legal misbehaviours), but much, much less accepted by the same academics who created it (with research failing to find any real evidence to support it, beyond the initial case studies). I'd argue that the zero tolerance policies it fosters cause far more harm to society (drug addiction being but a single example).
I think part of the problem here is that we are speaking way too broadly about this and lumping all drugs together.
If we are talking about marijuana, then I don't disagree with you. It should be legal.
Cocaine and heroin are more complicated.
Lets get some facts and start to discuss some of these drugs as separate cases.
Rate of addiction according to a 5 second google search;
There's another side to this though. How addicted do people get.
I don't believe anyone who is addicted to smoking is going to steal or kill to feed their addiction. It would be nice to get some stats on how addicted people get, if such stats exist.
What makes this drug particularly dangerous is that the dose that can cause death is only five times greater than the dose required for a high. Additionally, heroin has an extremely high risk of death from a relapse.
Having read this on the effects of cocaine, it seems like permanent psychosis is probably the most destructive outcome. Most of the others are either temporary or fairly minor by comparison.
I can't seem to easily find stats on how many people who use cocaine end up with psychosis. I think that would be helpful in this discussion if someone can find that information.
To be clear I never took a hard position that you are "wrong". My argument is just that this is complicated and although it sounds good to legalize it, you've framed it in a way that sounds really positive but it's not necessarily going to play out the way you think.
You're making the argument that it is wrong and unfair to treat drug addicts as criminals and I don't disagree with that but you're making an argument which to me is irrelevant.
If you had to kill 10 innocent people to save 1,000,000 innocent people, you'd do it, right? That's the way I'm looking at this.
If legalizing it will cause more harm than good then it's irrelevant how wrong and unfair it is to criminalize drug users.
Making the argument that it is wrong and unfair to criminalize drug users is wasting your breath because I don't disagree with you and it's not relevant to the argument that I'm making.