Lottery winners are barely happier a year later than before.
In 1978 Brickman, Coates and Janoff-Bulman compared 22 lottery winners, 29 accident victims with paralysis and a control group. Winners were not measurably happier than controls and even found everyday pleasures duller. Accident victims were less happy, but far less so than expected. Later long-term data show adaptation is real but incomplete; people hardly adapt to unemployment, for instance.
Useful: Before buying, ask how it will feel after six months, not six days.
Source: doi.org