I've come to this conclusion as I've grown older: Income inequality is far more important than income.
It doesn't much matter if everyone lives in a 2-bedroom house and rides a bicycle to work, or in a 5-bedroom McMansion and drives a Lexus. DDG for "hedonistic adaptation." Or travel to poorer countries.
What does matter is /stress/.
Right now, most Americans seem to be living in a state of high financial stress. Baseline costs, e.g. college debt, housing costs, medical costs, and similar take a majority of people's income. The remaining disposable income might buy more computers and TVs than in 1950, but that doesn't matter much.
What does matter is that, for example, the short-term job loss, a litigation, a divorce, or a medical problem can lead to cascading financial ruin. It matters that the cost of raising kids puts having a family out-of-reach for many, or just very, very hard.
The economy in, for example, the Soviet systems was far poorer, but on the whole, everyone was guaranteed housing, food, and basic medical. People were happy enough.
I have mixed thoughts on universal basic income, but as I get older, I find concepts like that more and more appealing (personally, I'm more a fan of universal basic food, medicine, and housing, with all the complexities that entails). I also find Chinese-style socialization of land and of finance more appealing.
Concepts like this date back to Rome. The poor in Rome were guaranteed grain: https://en.wikipedia.org/wiki/Cura_Annonae