As for the slight drift in US wealth distribution since 1980, it’s wholly explained by the change in age demographics. Since 1980 we’ve gone from a nation of people 30 years old to 40 years old. 10 years is a lot of time when it comes to compounding returns on productive assets (stocks, etc). Due to compounding, wealth held by each age group also gets more Pareto-extreme heading into retirement age.
Adjust that out, and this is mostly a nothing burger. But emotionally people don’t feel that way so nothing I say will change that. Narrative zeitgeist always wins over objective reality.
Average Americans are wealthier than they've ever been. Another chart to drive this home, the percentage of Americans who have a passport since 1989 (Note, this is also influenced by age demographics, but not as dramatically as wealth): https://www.statista.com/statistics/804430/us-citzens-owning...