Someone who studied this in Toronto by overlaying nighttime photos to find units where the lights are literally never on: https://www.movesmartly.com/articles/condo-units-sitting-emp...
https://www.reddit.com/r/badeconomics/comments/musne8/dispro...
https://www.blogto.com/real-estate-toronto/2021/02/real-esta...
This is just another symptom of the major lack of housing in the US, and needs to be solved as well, but it highlights how difficult it is to alleviate homelessness when there are other casualties of the housing market as well. By all means, build as much housing as soon as possible, but some of it will probably need to be specifically targeted at homeless or poorer populations.
[0] https://www.pewresearch.org/fact-tank/2020/09/04/a-majority-...
price = F(supply, demand) therefore demand = G(price, supply) and supply = H(price, demand)