Here's the best description I've heard of homelessness. It goes in stages:

1. You are evicted or priced out of your apartment or house. You are still working but you are now housing insecure. You might couchsurf, stay temporarily with friends or relatives or otherwise hop around until those options run out;

2. You are now living in your car. You likely still maintain a job. There's a constant cat-and-mouse with local authorities who will seek to tow your car or detain you if they find you living in your car. You might move around, sleep in Walmart parking lots and so on. At some point your car might break down and you can't afford to fix it, or it gets impounded and you can't recover it;

3. You are now living on the street. This is the first stage of homelessness that people generally see. Unfortunately visible homeless on the streets is largely viewed as an eyesore and people push local authorities to sweep them into a neighbouring town, city or county. Also, visible homeless is what drives people's perceptions of crime [1]. The same is true for the "migrant crisis" and visible (unhoused) migrants in places like NYC. Having no transportation, you will often lose your job (if you haven't already); finally leading to

4. You are longterm homeless. Because of this you likely have addiction and/or mental health issues as you self-medicate to cope.

Some (wrongly) believe that drug addiction leads to hojmeless. It's the opposite.

As for the cost of housing and homelessness rates, the link is well-established [2].

[1]: https://www.columnblog.com/p/people-feel-unsafe-because-visi...

[2]: https://www.pewtrusts.org/en/research-and-analysis/articles/...