Earlier quoted context omitted.
This generally doesn't happen for two primary reasons. First cities are not closed systems. Places like LA and the Bay Area have a built up demand that exceeds housing. The new housing would have to be added at an extremely high right to keep up with that demand otherwise the city just grows rather than becomes cheaper. When a city simply grows, the cheaper units never flow down to the bottom of the market as someone…
> someone else will move in who lives outside the city I don't really see this as a gotcha. Those would-be new arrivals to the city don't materialize out of thin air. Presumably they left some other place behind, and their migration is freeing up housing stock wherever they leave behind. The underlying dynamic is still the same. New housing increases low-end affordability by soaking up mid-end demand for old housing…
The difference is that housing costs take up a much higher percentage of wages in California than Ohio and as a result there are many many more homeless people in California than Ohio.
Sure, if you want to take a holistic view of the entire planet, the people have to come from somewhere and there is a finite demand for global housing. However that just isn't a practical way to look at it when the problems are localized. Different cities and regions have varying levels of desirability. It makes sense to build housing in those cities and regions for a wide spectrum of the population. The solution shouldn't just be "if you are poor, move to Ohio".