As someone who lived in South Bay for 5 years, I'd hardly call it a "desirable area".

Sure. Most of that desire is "I want a high paying job". With that goal, they sacrifice things like affordable housing, good schools, crime, congestion, etc.

Don't forget housing is stupid expense in NJ as well. I wouldn't call NJ "desirable".

This is true and explains some of it, but it doesn't change the fact that currently wanting to live in a desirable area and wanting to live in an area because of a job are conflated with no options that could effectively separate or distinguish between the two sources of demand. It's not like everybody would get up and leave the Bay Area, but it would allow those who only want the job to leave the market for housing in the Bay Area and lowering demand overall. At worst, the drop in demand would be supplanted with people who wouldn't move to the Bay Area at the current price (and thus the price wouldn't see much of a drop), but at least you wouldn't be crowded out by people who would leave the Bay Area given the choice.

West coast cities would be my definition of undesirable.

Survey says; a few people agree with you. Most do not.

Survey says; most people are lemmings.

People are happy and healthy in a place for all kinds of reasons. That doesn't make them a desirable settlement destination for others.

Maybe a town is incredibly racist and who lives there is all from the same longstanding community and they are all extremely close and have good personal relationships with each other and feel a strong sense of belonging to the place and the people. Maybe the town is perfectly suited to being students, young and single and there's a lot of things that cater to them. Maybe the town is better suited to families, couples, people who own dogs. Such people will gravitate there. This could mean they are all happy and healthy, but it would not mean that if I, some random bloke from a different state/culture/language/country moved there and tried to settle in and live my life, I would be particularly happy or healthy.

So yes, a place can be the happiest place in the world for the people who already live there, and still be undesirable for the "looking for a nice place to settle" population at large. However, having a highly employable, high income industry, lots of motivated hard workers, a vibrant art scene, and good weather makes a place a lot more universally desirable, and it takes a helluva lot of negatives to offset that desirability (which the bay area is trying really hard to do).

Yes, cheaper places exist. If you're offering up your geriatric, white, sleeper country club town as a superior place for tech workers, I'm not sure what to say.

Being the happiest and healthiest city doesn't really affect what's counted as desirable or valuable in the housing market. This doesn't really follow.

You know those are paid for and marketed by your local city's real estate industry, right?