By every medical or fact based study, marijuana, shrooms and LSD are among the safest drugs ever known. Psilocybin and LSD are completely non-habit forming; as in they are much, much less addictive coffee.
Meth is not some new drug. It was the typical biker 'speed'. And there were many years when the US was producing massive quantities of amphetamines for prescription use.
The vast majority of heroin users are not addicts, but occasional users. Similar to how the vast majority of people who drink are not alcoholics. The brain damage levels of alcoholics are incredible and much more severe what a cocaine addict has. (I am not advocating cocaine use; the heart attack rate is very high.)
The medical facts are a VERY different story than is portrayed and then there are problems like the complete lack of evidence prohibition reduced alcoholism. Alcoholics made sure to get a dealer.