There's a point here being missed by many commenters. People have trouble realizing future happiness today. The extra $75k/year you're putting in the bank is essentially going to be paid back to you after you stop working. This is going to contribute to your happiness (in the future!) at the same rate as going from $0 to $75k does now. So the study is reflecting that people undervalue their future happiness. Which makes sense, as you could get hit by a truck tomorrow, so future happiness isn't as valuable as the same amount of happiness today. That said, there are clearly diminishing returns involved as well, so I don't discount the study in its entirety.