And actually, when you have people going to the black market for relatively benign things like weed, mushrooms, coke, ecstasy, etc, you expose them to these things getting cut with opioids, and developing an addiction they may never have intended. Why? Because it's profitable for drug dealers to have addicted customers.
The more interesting question to me is why you think prohibition still suddenly start working.
This isn’t directed at you just a general statement. I find it strange that the narrative now is that the drug epidemic in “rural America” is being blamed on the government “loose borders”, “illegal immigrants”, etc.
But when it was happening in the “inner city” it was all about “poor morals”, “the nation getting away from God”, “out of wedlock pregnancies” and “absentee fathers”.
Also the War on Drugs has also been used to statistically target minorities and give police an excuse to abuse their power.
If legalizing drugs takes power away from the Justice system to criminalize behavior that hurts no one but the participant, I think that’s a win.
The hard stuff causes the societal problems you saw. Marijuana and mushrooms, can't speak for LSD yet, create personal problems but not societal ones. Despite that, they are still widely prosecuted harshly. Legalizing marijuana and shrooms is a step to separate those drugs which are a personal issues, and those which create societal issues.
The most dangerous things about these substances is that it's hard for a person to be sure what they're buying. If someone wants to purchase marijuana or psilocybin in a state where it is illegal, you have to go through shady channels to get it. Hopefully that psilocybin pill is just psilocybin, but maybe whoever made it laced it with something addictive, or maybe it wasn't processed in a sanitary way. Who knows? When these substances are legalized, their production can be regulated and inspected like anything else.
All that said, if an adult is caught with marijuana or psilocybin, they can face serious legal consequences and jail time right now, depending on where they happen to be in the country. That can ruin someone's life. And even though marijuana use doesn't vary that much by race, marijuana charges are overwhelmingly used to jail Black and Hispanic people, which just exacerbates race issues in the USA. Having these law on the books is doing way more harm than marijuana (or psilocybin) ever did. Let's get rid of them!
For hard drugs it can probably help centers do things like safe injection sites. Legalization also means you can regulate. That can help in a lot of ways: making drugs safer, mandating that done portion of proceeds gives towards prevention, etc. Addicts will be less afraid of seeking medical treatment if they know they won't be in legal trouble. (They wouldn't anyway, but I've heard a lot of people are paranoid about this.)
Anyway, I don't have any facts or figures. But it seems reasonable to me that legalization could, in some cases, help.
If you can believe it, there is more to California then downtown San Francisco.