Senator Warren's boom the Two Income Trap says that in the US the second income went mostly into higher land prices, childcare and transportation. The net benefit accrued mostly to the old (more workers per retiree), the government (more work now taxable) and the rich (who held assets that rose in price).
The problem isn't that there isn't enough income it the distribution of the income.
The problem isn't that there isn't enough income it the distribution of the income.