Interesting article. People are nitpicking different issues but not many are addressing the core idea, and that idea I think is sound, regardless of the coefficients picked and so on. Inequality is rapidly increasing all over the world, it is cumulative and self reinforcing (people in power using their unequal wealth to pass laws making inequality even worse). Sure, maybe median income is steadily increasing. The enormous accumulation of wealth on top would quickly render income increase meaningless. Anecdote to illustrate - just yesterday someone took a photo of a new apartment complex (so already not a luxury segment at all) with an ad on a fence "new apartments for your collection". For "collection". So they already know who their market is - wealthy guys/corpos buying housing in bulk to flip for profit or rent. Today it's an isolated joke, tomorrow it will be a standard. Same with everything else - private transportation, above average education, even knowledge work would be a prestige thing.

Combine that with disillusioned poor strata electing right-wingers in hopes of solving inequality via xenophobia, but afterwards getting autocrats who are only interested in the personal enrichment and burning wealth ladder even faster, plus blocking any option to return to centrist government to preserve power (see Russia, Hungary etc.). The cumulative outcome of all of this is rather bleak. But median income will be a few percents higher, yahoo, amazing.