1) Drug addiction (addicts and the mentally ill are no longer rational actors and it's cruel to treat them as such, stop paying them to sleep on the sidewalk)
2) Immigration (like it or not, pumping up demand weather they're paying for it or the government makes housing much more expensive for everyone.)
3) Cheap credit (Everyone knows how this works and worse still it directly effects the most disadvantaged while funneling their money to the wealthy.)
4) High cost of construction labor
5) Material supply chain issues (which is largely the same as the last two, it's all just inflation.)
6) Expensive regulation that adds to construction cost (zoning, building codes etc.)
Housing is part of it but not the only part. Some of these things could be easily fixed in ways that benefit everyone who lives here (housed or not.) No one in charge wants to though and you should be asking why.