Up until 2017, the price of a house had been creeping up, but so had the size of the median house. One you adjust for inflation and square foot, it was pretty steady.[0]
[0] https://www.supermoney.com/inflation-adjusted-home-prices/
[0] https://www.supermoney.com/inflation-adjusted-home-prices/
There is no option to rent 500 square feet because it's illegal in most cities to have units smaller than 600-750 square feet.
Cui Bono
I think the takeaway isn't that material living standard in the U.S.A. have declined but that they've only increased a little.