First of all, we don't have to propose an imaginary conspiracy to acknowledge the reality of how we came to think about drugs the way we do: it is documented that the intent of the controlled substances act was to justify criminalizing the political opponents of the Nixon administration. But the downstream effects of this, aside from making medical care much more difficult to access, has been a large amount of money funneled into propaganda that blames drugs for a wide swath of society's ills while also needing to claim that the act of using the drugs was a personal moral failing, in order to justify the carceral approach we have taken to violations of this law. The "evil organization" that puts out a lot of this stuff is only loosely affiliated, usually local law enforcement orgs, though usually federally funded to some degree, the motivations for scaremongering in this way are obvious enough that no conspiracy is necessary there either: they benefit from the fear of the poor, the homeless, and the drug-addicted in a direct, financial way. By now many of them are staffed entirely by people who have grown up in this propaganda-filled environment.
Scapegoating the poor as depraved criminals is a time-honored way of muddying the waters about economic issues that need resolving, and while doing so openly has fallen out of fashion, most people alive today have consumed enough fearmongering and misinformation about drugs that tying drug usage to issues of poverty is an easy way to launder that kind of messaging, and so that kind of messaging is pervasive. So pervasive that you don't even believe that it comes from anywhere, just that it's the obvious truth. In reality, there are tons of high-functioning drug addicts, and the high-functioning part has far more to do with affluence than what drugs they use, just like homelessness, in turn, has more to do with the housing market than it does with drugs. This would seem obvious to me, but what is "obvious" is not a function of some objective universal reality, and only really comments on the subjective context of any given person claiming "obviousness", including both what they've experienced, and what they've been told
When the incentives are strong enough, no conspiracy is necessary, especially when the tricks being used are old and battle-tested ones.
Also, as far as spending other people's money goes, I'd much rather governments be spending mine on mitigating the housing crisis and its downstream effects on individuals than funding law enforcement to harass and make life difficult for society's most downtrodden. Police receive outsized budgets to "clean up" homeless encampments and endlessly violate people's privacy, autonomy, and often bodily integrity in the name of an endless draconian crackdown on the contraband that you would have me suppose is responsible for the existence of the homeless. Even an inefficient approach like funneling some of that money directly to individuals stuck in poverty traps seems a lot more likely to actually make a dent in the problem, rather than constantly exacerbating it. I bet it would be cheaper, too