[randomdata]

> what central mechanisms changed around 1980?

The Copyright Act of 1976, perhaps? If we look at the list of wealthiest Americans, most of them are there because they provide something to the world that nobody else is able to directly copy. Without competition, there is no mechanism to spread the money around.

[nateabele]

This would certainly disproportionately impact authors, entertainers, and anyone else who makes royalties from media, but I don't know that they represent a large enough swath of the economy to account for the broad trends we see here.

To my original point, though, making money off of a copyrighted work represents income from an asset, the value of which compounds over time, due to inflation.

[randomdata]

> I don't know that they represent a large enough swath of the economy to account for the broad trends we see here.

I'm not sure it is that broad to begin with. The 99.999 percentile of adults with these near-infinite income gains represents only ~2,000 people. While wealth and income aren't the same thing, I expect there is a lot of overlap with this list[1] that outlines 400 of the potential names.

If you look at how they made their fortunes, many are directly attributable to copyright. Bill Gates certainly wouldn't have topped the list if anyone was free to copy/resell Windows.

> To my original point, though, making money off of a copyrighted work represents income from an asset, the value of which compounds over time, due to inflation.

Increased value of an asset does not necessarily translate to increased income. A primary residence, for instance, is a good example. The value of your home may be increasing, but nobody is paying you to live there. Many people are quite happy to pay top dollar for an asset that generates no revenue on the hope that capital gains alone make the purchase provide returns.

But you do rightfully point out that those who have entire control over a certain asset have complete control over the streams of money directed at that asset. That is not exclusively limited to copyright, but changes to copyright opened up a whole new set of wide-ranging assets to hold that were previously not there. Anyone holding hard assets was presumably already milking it for everything it was worth, thus, while incredibly profitable, not increasingly profitable.

[1] https://www.forbes.com/sites/chasewithorn/2016/10/04/forbes-...