Who is building these unbelievably gaudy houses? And who is buying them?

I hate prissy HOAs as much as the next guy, but good lord could we use some "neighborhood context" guardrails around what you can build in the single-family home areas. Every year another tasteful colonial revival or Tudor-style house gets torn down and replaced by one of these Temu McMansion monstrosities. I won't post pics but you know what I'm talking about: random huge columns, pointless arches, marble galore, 2 BMWs in the gated driveway. Mainly right off the Grand Central near the high school, but they're spreading.

Where is the demand for these coming from? Do the owners think we are impressed? And are there still contractors who know how to renovate actual nice houses?