Clearly, the value of education is far more than the earning power it enables. Not only does it open doors for one to achieve his or her highest potential, but it is essential to a properly functioning democracy. Money may not be the only objective, but there is a clear overall correlation between income and educational achievement.
In developing countries, the education of women in particular is seen as a key to upward social mobility and minimizing world poverty.
Note: The chart above was copied from a bulletin board in the hall at Shasta College and presents data that I know is a decade out of date; however, the relative differences are still probably still correct.