Economic cycles run in decades, hence you need to look at terms longer than decades to see if there is sustained improvement or not. From 1986 to 2019, there was gain at the median. [2; Table H-6] shows that since 1975, the median household income has increased by an annualized 0.7%. Each of the dips in [1] correlates to macro-economic events such as the '89 recession, dot-com/Y2K thing, sub-prime mortgage crisis. When the 2020 number come out, we'll likely see another dip due to COVID.

None of those events were precipitated by wealthy persons somehow screwing the poor. The sub-prime crisis comes the closest, but many wealthy persons were also affected badly by that policy error. The entire workforce of Lehman Brothers, for example.