You are probably on to something with the lack of "retirement" (US, business and academia). Also, the change may lead to less happiness, from breaking such a long-term "routine" (I would say "life").
It seems like with enough time we become institutionalized to a certain way of life and will reshape our happiness to fit perfectly to that world.
Oddly, first time I saw the world this way was after watching Shawshank Redemption as a kid and seeing Brooks killing himself after he was freed. From that point on, a lot of the seemingly irrational decisions people make made a lot more sense to me.
