Most of those people on the streets in SF and elsewhere on the coast are originally from somewhere else. They gravitate here because the weather allows year round outdoor living, there's a permissive drug culture, and more and more money keeps getting shoveled at the problem.
But most of those homeless people CBers like to laugh at living on the streets of SF were born in places like Dubuque and Provo and Oklahoma City, victims of the nationwide opioid crisis.