I guarantee for every "homeless junkie" in SF or any city, there are dozens if not hundreds of functional and semi-functional substance users. Don't get me wrong, the nature of some drugs, especially heroin/fent, meth, cocaine, and alcohol, mean a significant percentage of users are going to completely fuck up their lives and the lives of those around them due to addiction.

It's weird how with illegal drugs we tend to blame the drug and the user, whereas with alcoholics, nicotine addicts, etc we tend to only blame the user. Does your opinion hold, that we should also not "live and let live" with dysfunctional homeless alcoholics? Believe me, they also make a mess of themselves and the neighborhoods they camp out in.

Anyway. Addiction is a beast. But using intoxicants to escape, augment, and/or enhance reality is a basic part of human (and animal) nature. On HN we all love to talk about incentives guiding behavior. Well when your life has been shit and likely will be shit indefinitely (due to health, social, economic, and other factors), perhaps in spite of any effort you are capable of implementing, the incentive to get some kind of enjoyment out of it anyway, regardless of the cost, is pretty damn high.