Comment by defertoreptar

Here is an image that plots the effective capital gains rate from the 1950s to recent years: https://en.m.wikipedia.org/wiki/Capital_gains_tax_in_the_Uni...

Let's analyze three periods:

1953-1985: no significant trend in effective capital gains tax

1985-1996: upward trend and higher capital gains tax

1996-2020: downward trend

Now let's compare those periods to real median family income (which tracks to 1953). https://fred.stlouisfed.org/series/MEFAINUSA672N

Annualized growth in real median income:

1953-1985: 1.8%

1985-1996: 0.8%

1996-2020: 2.0%

Real median income growth during lower capital gains tax policy was twice that of the period of higher capital gains tax policy.