Most people are overconfident -- even though not everyone is above average. Given the choice beyond systemic underconfidence and overconfidence, I can see arguments for the latter. Animal Spirits will probably do more to end the present recession than all of the industrial policy coming from the political establishment. Indeed, we hope that the former is not defeated by the latter.
This study reported in the May/June 2009 Federal Reserve Bank of St. Louis Review presents findings from a study that corroborates that overconfidence is international. And, other things equal, less of it is shown by males.