I find this article misleading.

> ... the upper middle class ... controlled 52.1 percent of total income in 2014, up from 29.6 percent in 1979. But had their income growth kept pace with their population expansion, they'd only control 48 percent.

So their income grew from a population-adjusted 48% to 52.1%? That's relatively minor, I wouldn't even call it thriving.

Also, don't the majority of actually rich people earn wealth via means other than income?

EDIT: The HN title is "America's upper middle class is growing", the link has the title "America's upper middle class is thriving". I'd agree that it's growing, but thriving is a hard sell given what's highlighted in the article