Modigliani: people save for retirement decades before they need the money
Franco Modigliani and Richard Brumberg argued in 1954 that people try to keep spending roughly stable across their whole life, borrowing as students, saving through peak-earning years, then drawing savings down in retirement. Current income barely matters; what drives spending is the total resources someone expects over a lifetime. The theory reshaped how economists model national savings and pensions, and fed into Modigliani's 1985 Nobel Prize.