Earlier quoted context omitted.
There are a lot of places where there is enough land to build more and more, but the governments don't allow it. And there are also places such as san-francisco, where replacing single-family houses with apartment buildings would solve a lot of the housing crisis, but the government (and NIMBYs) don't allow it.
Even in a world with zero building regulation you're still running into constraints though. Sure, people could build more apartments which would slow growth in accommodation prices and maybe directly hurt the value of the neighbours' properties they overshadow, but land is still limited amd expensive (more expensive if you're allowed to build tenement blocks on it) and construction still physically intensive and expe…
After a bunch of regulation, now, the "papers" cost more than materials to build, and most of the area is zoned as eg farming area, even though there has never been any farming there. Of course, prices have gone up A LOT, there is a lot of NIMBYism, by people who already build their house, and don't want another one next to it, and young people are basically fucked.
We might disagree, but in places with available land (and there are many), the only thing that stands between housing and non-millionaire people are (local) governments and regulations.