From my conversations with people that work with the homeless as well as formerly homeless people it is not only cost of living, housing, but also addiction, mental health, and loss of community/family.

It complicated basically but it is a major sign of not only economic decline but also moral decline. There is no question that some of the cities with the most restrictive zoning have incredibly high cost of living and homelessness rates. Not only this but the incentives for the city governments is NOT to solve this problem but to virtue signal and spend money.

One person that works with the homeless says the single biggest factor is loss of community. It is a total breakdown.