Every study shows that the overriding cause of homelessness is the lack of affordable housing.
Is there drug use in homeless populations? Of course, there’s also a ton of alcohol use as well. Is it the cause of homelessness? No.
Because we have statistics from other states with much higher drug abuse and OD stats that have lower rates of homelessness, because the driving cause of homelessness is not being able to afford a home.
Hell even HN had a post on this a week or so ago, the dominant factor - more than laws, environment, social support - is housing costs.
The other thing people don’t acknowledge that the denser your population the more compact - and so pronounced - the homeless populations become. A few years back there was an article about how Boise didn’t have the SF homelessness population due to punishing the homeless. Except statistically they had basically the same number, but doesn’t have anything like the population.