It seems like the main point is that people shouldn’t buy or build houses which are at the limits of their finances, available maintenance time/abilities, and/or space needs, because future changes might push them past those boundaries and force them to move. In many cases people who vastly exceed their own needs end up with a house nobody else wants afterward.

It is not as far as I can tell arguing that every possible “dream house” falls into that category.

Personally I can’t imagine ever wanting a house of >2000 square feet, which would already comfortably fit a large family. But I have several friends with giant mansions full of rooms they never use.