We are the global elite who could have done things differently

Doesn't the following chart tell one heck of a story:

[The] take of the very rich peaking in the late nineteen-twenties, at close to twenty per cent of total income, then falling sharply for forty years, only to turn back up in the late nineteen-seventies, and peak again in 2007.

Cassidy links to this paper, where the authors provide a similar looking chart for changes in the top income decile:

The question is always the same, right: why bother about income distribution?  Among other reasons, we want to understand how much of the national income goes to the top one and ten percent because of:

their impact on overall growth and resources, their impact on overall inequality, and their global significance.

At the same time, keep in mind that:

In the grand scheme of things, even the poorest 5% of Americans are better off financially than two thirds of the entire world

So, at the end of it all, could we have done things differently since the late 1970s, which is when we notice the sharp uptick in the graphs?

Yes, without thirty years of rising inequality, and with the same overall national income, income of the middle class would have been greater. People with middling incomes have many more priority needs to satisfy before they become preoccupied with the best investment opportunities for their excess money. Thus, the structure of consumption would have been different: probably more money would have been spent on home-cooked meals than on restaurants, on near-home vacations than on exotic destinations, on kids’ clothes than on designer apparel. More equitable development would have removed the need for the politicians to look around in order to find palliatives with which to assuage the anger of the middle-class constituents. In other words, there would have been more equitable and stable development which would have spared the United States, and increasingly the world, an unnecessary crisis.