The article answers its own question, if simultaneously partially and at great length. It's as simple as this:
(1) The wealth is not evenly distributed.
(2) Living in America is extremely expensive relative to other parts of the world, and it's impossible to emphasize this enough. (The mandatory insurance requirements are painful, cellphone/internet service is much more expensive, and I can go on all day.) So the average American might have more money than, for instance, the average Bavarian -- but also spends a lot more for the same goods, and in the end is not meaningfully better off. And it feels worse, because you feel like you're being ripped off all the time.
> Wealth always tempts us to be discontent. We’re cursed with that insatiable desire for more. We’re prone to envy. There is a reason we talk about keeping up with the Joneses.
I think this is one argument for a more progressive income tax (and/or a wealth tax). Sure, a sharply progressive income tax incentivizes work by low income people, but it also reduces the wealth and income of high-income people, indirectly making them and everyone happier.
https://archive.ph/HfXMr
Is it because material wealth does not equal happiness? Probably the reason why all major religions teach that the true path to peace and fulfillment is found within austerity.
My theory has been because deep down inside we know so many things said about the US are lies. Our super-individualism, judgementalism and focus on money, family is not #1 in the US, it might be #3. #1 is your personal freedom above anyone else, family or not, then money is #2
Because the only emotional reward is violence.