Who are the people who live in 2mm+ houses?

Folks, this is our first year in the U.S. and we're really curious how do people afford to live in such expensive houses like in River Oaks (2mm, 5mm, 10mm)?

Is it a place where businessmen, sportsmen, and senior managers live? It is not envy, we're just very interested and didn't have a chance to ask the locals.

These houses are so shiny that I have a constant feeling that they are all for sale. Property taxes for most of these houses literally exceed our annual wages 🙂