People making 300-500K are rich in my view.
In Denmark we have something we call toptax in our progressive system. Its around the 81K$ mark and alot of people pay toptax to put it mildly. But its not the big issue as you portrait it. Because you have to remember that for the entire income below, you dont pay it. So the effective taxrate aint changed much until you start to essentially earn ridicious amount of money.
Also how many american families even earn above 250K? Not that many.
Back in the 40s and 50s and early 60s. the US tax system actually had a system against money hoarding and the crazy wages. There was up to some 90% top tax. The economy in the US was blooming back then. After it was removed, what happend? Downturn and a more unequal society started to emerge. managers and directors etc increased the wage differences between themselves and the employees with over 30x. Everytime that happens its the man on the floor that loses. the result today is that 400 americans sit on the same wealth as the rest of the 300million. That means they are 750000 times more wealthy than the average of the rest. And its destroying the economy and society.
The same applies for corporate money hoarding that aint released into productive investments. Apples huge cashpile for example is invested in a hedgefund that is directly damaging to regular people.
Another example would be this, 2000 to 2006 was a booming time. Yet barely any americans benefitted from it. However those that did really took their slice of the cake.
If the uneven prosperity chart included capital gains, It would be even more stunning.