After Prohibition, the underworld mob had to find a new source of income. Heroin was the new drug of choice. LA and New York were flooded with high profit heroin.  The cool jazz, and beat under-ground of New York , and even much in Hollywood, from 1940 - 1960 were riding on heroin addictions.  It is all well documented. The same will happen when cannabis is legalized. We are already seeing the first wave of new drugs like fentanyl that will keep money flowing to the global underworld.  Worse is yet to come. It doesn't matter what a new drug is as long as it is addictive and make lots of money.

As more and more people die from bad drugs, we will simply get used to it.