A recent study published in Perspectives on Psychological Science, has found that the happiest people are not necessarily the most successful, in terms of money and (for students) grades, attendance, etc.

The 10s earned significantly less money than the eights and nines. Their educational achievements and political engagement were also significantly lower than their moderately happy and happy-but-not-blissful counterparts.

In the more social realms, however, the 10s were the most successful, engaging more often in volunteer activities and maintaining more stable relationships.

The student study revealed a similar pattern in measures of academic and social success. In this analysis, students were categorized as unhappy, slightly happy, moderately happy, happy or very happy. Success in the categories related to academic achievement (grade-point average, class attendance) and conscientiousness increased as happiness increased, but dropped a bit for the individuals classified as very happy. In other words, the happy group outperformed even the very happy in grade-point average, attendance and conscientiousness.

Those classified as very happy scored significantly higher on things like gregariousness, close friendships, self-confidence, energy and time spent dating.

No argument there, but check out the conclusions one of the authors comes to:

The data indicate that happiness may need to be moderated for success in some areas of life, such as income, conscientiousness and career, Diener said.

How warped does your value system have to be? Ignoring causation/correlation (happiness may not necessarily affect income- in fact a personal emphasis on making money has been shown to make people less happy) Diener needs to get his priorities straight. For his edification:

“volunteer activities and maintaining more stable relationships” > “money”
“gregariousness, close friendships, self-confidence, energy and time spent dating” > “grade-point average, attendance and conscientiousness”

and finally:

happiness > success