>> Sobriety and self-control are essential to a functioning society and especially a liberal democracy. Freedom, to the extent we have it, requires that we can govern ourselves.
Yes, but we tolerate alcohol. We tolerate getting high - but we are selective about which drugs you can get high on. If we tolerate alcohol, so why don't we tolerate cannabis, psychedelics and other "soft drugs"? It's because of misinformation, fear, taboo and stigma.
>>>> People are always going to take drugs, and by and large, they are harmless
>> This is an argument that has never made much sense to me. People are always going to commit every crime. Laws exist because people will break them. And laws are effective deterents if the penalties are appropriately harsh. Consider that alcohol consumption took almost a generation to return to its pre-prohibition levels (around the 60's-70s').
But if you criminalise behavior that does not really harm anyone else but yourself (at most), you're inventing a victimless crime. Victimless crimes do nothing to help society - in fact, it degrades society, marginalizes and criminalizes otherwise respectable citizens, and in case of drug prohibition, guarantees that drug money goes to black market, which in turn potentially increase violent, real crime.