A year or so ago they surveyed the homeless in San Diego. Everyone assumed that the homeless population is largely from out of state, coming to SD to be warm while homeless. What they found was the complete opposite.
Most of the homeless do not have a drug problem or only started taking drugs after becoming homeless. Most homeless people were employed full time for the 12 months before they became homeless. Most homeless people in San Diego were born there and watched as the relentless march of 5-10% increases (California state maximums) slowly pushed them into homelessness.