Edit: I support UBI. I just don't think UBI is sufficient to solve the problem.

The homelessness problem is caused by the fact that extremely restrictive building codes make housing so expensive that it's impossible to pay for without a significant income far beyond minimum wage.

UBI probably won't be possible at an income level that pays for the inflated price of housing.

Restrictive building codes are necessary in high density population centers. And if you are in a place prone to natural disasters or whatever, codes are necessary. They are optional in most low density living options. People lived for ten thousand years without building codes in low density villages, and they evolved really cheap but reliable ways of building.

The Romans figured out how to make sewage systems work, and it's pretty easy to replicate them nowadays. All you need is some bricks, and a thousand men with shovels. Sewage systems are not a big bottleneck. It's the crazy complex restrictions. This is true for all advanced democracies. It's illegal for a person to build his home cheaply and with abundant cheap materials. The law always mandates extremely specific, expensive materials. Sometimes the materials that are required by law are hazardous to health, and the safe cheap local materials are illegal.

It's a men's issue because the majority of people intending to build their own safe, inexpensive homes are men.

Edit: Markets don't magically provide homes for people. Compliance with all the various codes, including the unnecessary ones, adds at least a hundred thousand dollars to the price of construction, in the overwhelming majority of cases. That places a floor on the power of the market to reduce costs in construction.

Also, people keep mentioning "cheap places to live". But maybe most of the landlords don't want to rent to homeless people and will demand an extremely high rent to prevent that from happening.

UBI fails to address the problem.