Regrettably the study does not mention another factor, how free-trade, particularly with China and East Asia generally, helped drive wages in the US at the bottom ever lower. The Reagan era produced a perfect storm of screwed for the bottom half in America.
Here:
Where does homoploutia come from? The data do not allow us to determine that with certainty, but they allow to investigate what is consistent with individual hypotheses. There is strong evidence that increased wage-stretching that began around 1980 is associated with the rising homoploutia (the other alternatives that do not perform as well are rising inequality of capital incomes and rising capital share).
The link between higher inequality of labor incomes and homoploutia might have occurred in two ways. The first is that many high-earning individuals saved a large share of their wages, invested it, and after some years began receiving large capital incomes. The second is that many capital-rich people decided, perhaps because of changed social norms, or because top jobs became more lucrative as marginal tax rates were reduced, not to treat university education as “luxury consumption” but rather to use it to secure good jobs. It could be, of course, that both mechanisms were at work.
