If you divided all the stocks issued in the US stock markets by issue number
and put them in a basket, chose one randomly,
there is an 87% chance that that specific stock belongs to someone in the top 10% of wealth in the country.
There’s either millions or billions of stocks in existence, but this is still true.
One of the most important drivers is the abolition of wealth taxes in the 70‘s. Although there is no exact date on which it happened (since wealth taxation in the US was fairly complicated, and rolled back over several decades); the 70s certainly played a pivotal role.
With no wealth taxation, nothing stops the ultra rich from amassing all the wealth, outcompeting workers and middle class. That’s what you are seeing here.
The good news is: all this productivity increase was real. The wealth increase is real. We just have to give it back to the ordinary people, and will see a massive economic boost across the globe. There’s just one little thing stopping us: we gotta tax the ultra rich ;-)