Several studies have concluded that people acclimate very quickly to increased earnings. People are happy with a big raise in pay initially, but the affect fades pretty rapidly. They become accustomed to the higher salary and view it as normal. At fairly high income levels you can actually develop a warped sense of what a normal, or "middle class" income is.
I see it every day with people who make upper six and seven figure salaries. Most of them don't feel rich partly because they know people who make more. They complain (as does the above article) about the cost of living in NY; the high real estate prices (of large houses in the nicest neighborhoods); the cost of private elementary school (when public schools are available); the nanny (also known as “Mom” & “Dad” to real middle class families); the cleaning service (ditto); the landscaper (ditto), etc, etc. They don't, however, stop and compare their financial situation to that of their administrative assistants who also somehow manage to live in NY on a 10th or a 20th of their income.
Just because you can find more things to spend money on than your income can support doesn't make you middle class.