I think the disconnect is that these people have an Upper Class salary nationally (the student linked at the top), but choose (and I stress the word choose) to live a middle class lifestyle locally.

For instance, with that upper class salary they could likely get a home outside the city with a pool, park a couple expensive bmw cars out front and go on expensive vacations, buy the latest toys, etc.

Or, they can live close to work/coast/lake/whatever and be house-rich, but poor everywhere else.

Middle-class people don't have such an option. Their salary leads to outskirt/suburb house without pool, without bmw, etc. And no option to live close to what they desire. People in the bracket sniffing the upper-class usually buy token "I'm rich" status items (designer clothes/phones/etc) which they can't really afford except maybe sporadically.

Poor people are worse off, they live in location with an x-block radius they rarely leave.