- Giving of gifts tends to make givers happy, even happier than spending money on themselves. .
- Gifts that are felt to be unearned tend to make people unhappy in the long run. For example lottery winners and such tend to in the long run do pretty badly in the long run.
For those who don't believe in "evil", replace instances of "evil" with "negative" or "harmful" or whatever similar word suits your fancy.
This talk is what got me thinking about this question.
1. Elizabeth W. Dunn, Lara B. Aknin, and Michael I. Norton (21 March 2008)
Science 319 (5870), 1687. [DOI: 10.1126/science.1150952]