homeless nor are they they root causes. I work in downtown San Francisco, and the majority of the homeless I encounter are there due to either mental illness or drug addiction. People rioting about gentrification and tech growth are barking up the wrong tree.
You are right about one thing: policy. San Francisco opens their arms wide open for drug users, and not in a good way. They've made it one of the most accommodating cities for drug use and it draws in people who do that like a magnet.