If You Are So Smart, Why Aren't You an Entrepreneur? Returns to Cognitive and Social Ability: Entrepreneurs versus Employees
Found something interesting at http://ideas.repec.org/p/iza/izadps/dp3648.html
The smarter you are, the more money you earn -- so far not very surprising. The interesting result, however, is that this works better for entrepreneurs than for employees.
So, in effect, if you are smart, you should be an entrepreneur.
I wonder how much of that effect can be explained by selection, both self-selection and external selection by bankruptcy.