My supposition was intentionally exaggerated to clarify what happens when you don't build enough housing: not to be pedantic, but understanding what happens in "extreme cases" is a common technique in math and physics to understand what happens in more common ones.
(Alternately, if no luxury unit is built, many of those buyers will be forced to buy the best-of-the-rest if they want to move in, putting more pressure on the middle, which in turn puts pressure on the affordable.)
The only place cheaper housing is being built are in developments on the far outer suburbs of flyover cities. But even those builders are having trouble with supplies and labor.
The pools are unused most of the time, but having a pool in the building increases the value estimated by property appraisals' checklists.
Apparently you haven't met my neighbors.
Why would you suppose that? I don't really see what you're getting at, that's a very unintuitive assumption; it shouldn't happen if market forces are allowed to run their course.