Many of those crack addicts became so because the lesser drugs, they thought they were buying, were laced with more addictive substances, because there is no incentive for pushers to ensure a safe supply, but the high prices most drugs currently cost gives pushers the incentive to get people addicted, because no rational person would buy a drug that would cause intense addictions.
No rational person would buy alcohol?
I don’t think rational calculation has much to do with the decision to use mood altering drugs.
Assumptions and conjecture. We have no data. Even if you are right the fact remains that the current population will continue to prefer hard drugs over mild ones. We do not have the luxury of starting fresh.
...no rational person would buy a drug that would cause intense addictions...
Plenty of rational people knowingly use highly addictive and dangerous drugs. Many assume that "it won't happen to me." Some feel pressured to participate regardless of the risks. A sizeable fraction have given up and simply don't care anymore. The reasons go on and on. The addicts that I have met invariably still think that they are in control. The hardest part of dealing with addiction isn't getting the addict to come clean, it's convincng him that he has a problem in the first place.