> using real estate as a fiat currency

Even if we take your premise as a given, the entire reason real estate is so valuable is that there isn't enough housing in the first place. Real estate is, by its nature, a bad investment; it's only the scarcity of it that makes the value continue to go up exponentially.

> buying up available real estate just to make it unavailable

There isn't actually any available housing in the first place, at the point of cities even approving projects, compared to the number of people who need housing. That's the problem. The most extreme example is San Francisco, where as of this July the entire city had approved only 16 housing units [1] out of an already comically poor goal of only about 10,000 housing units per year.

[1] https://www.newsweek.com/san-francisco-only-agreed-build-16-...

>Real estate is, by its nature, a bad investment; it's only the scarcity of it that makes the value continue to go up exponentially.

It's very nature is it's scarcity though. Land is the one thing they don't make more of.