Lots of rural areas and small cities have broadly shared prosperity too. I was very surprised when I went to East Texas and saw the brand new strip malls and shiny pickup trucks everywhere. (Along with a very racially diverse and integrated population driving those trucks and eating at the new big box restaurants. I was completely unsurprised to see Trump doing better than expected among Latinos in Texas.)
NYC, DC, and SF are probably the only cities I’d put in that category. Maybe Seattle. That’s only 12% of the population.
The median household income in San Francisco is $120,000, but the median home price is $1.5-2 million, depending on source. That's 12-16x.
A $500/month truck payment isn't putting people on the edge of financial ruin when you're talking about an $800/month mortgage versus a $6,500/month mortgage.
Rust Belt decay is obviously less conducive to happiness, but I think “boom towns” (where a marquee industry makes a small percentage of the population very rich) also aren’t conductive to happiness. Might explain why the politics out of place as like San Francisco is so apocalyptic. People want to have a normal life but the economy of the city has bifurcated the population into “rich but stressed out” and “struggling to get by.”
To be fair I get the sentiment. DC was the same way. In DC it was childless wealthy professionals on one side (mostly white and Asian) and service workers on the other (mostly Black and Latino). It was depressing as hell and we had to get out.