In almost all measures of the Gini coefficient two significant flaws exist:
1. Incomes are counted on a pre-tax basis
2. Incomes are counted on a pre-government transfers basis
The consequence of this is that income inequality appears to be increasing _regardless_ of the level of social subsidies and redistribution.
When you correct for these measurement flaws, income inequality in the US has been decreasing over recent decades.
If you are in the “Tax the Rich” camp as a result of looking at the Gini coefficient, you may need to strongly update your priors.
Sources:
https://www.wsj.com/articles/incredible-shrinking-income-ine...
https://www.economist.com/briefing/2019/11/28/economists-are...