Same old tired argument, I see. Everything goes back to prohibition because you don't have a logical defense for legalizing additional carcinogenic drugs.
Prohibition failed because a legal industry that had a long-ingrained heritage in our nation's history became criminalized. As a consequence, everyday citizens outside of the temperance movement thought the Volstead Act was a joke (which it was).
Apart from the "elixirs" of the 19th century (most of which were comprised of alcohol mixed with opium or cocaine), no such history exists with respect to the illicit drugs of today.
But as I said from the start, I think people should be able to fry their brains any way they see fit...so long as they sign away any claims of benefits or special treatment from society and its aid programs.
Your right to be an irresponsible doper ends where my tax bill begins.
Now that I've answered your question, answer mine: Would you prefer to be a passenger in a plane with a pilot who abstains from all mood-altering drugs, or a pilot who smokes dope and shoots cocaine?