Naples has more millionaires per square mile than any other place in the US.
The median home price in Palo Alto is 2.9 million dollars. 56.3% home ownership rate. Housing values have doubled in the last decade, so even someone buying a median price home 10 years ago at 100% financing has 1.5 million in equity.
And because unlike Naples, those homes aren't a lot of empty nesters, there are more millionaires per home, for example the Zuckerberg househould has, for all intents and purposes, four billionaires.
And while it *should* be denser than it is, there are a lot of multi-million dollar homes on 1/8 acre or smaller lots, and plenty of duplexes.