<p>@vossron: This statistic expresses correlation between educational level and income. However, correlation does not imply causation.</p>
<p>People who earn a college degree are, on the average, more intelligent and motivated than those who do not. Even without the college degree, those traits still enable one to earn more money. Thus, someone who would have earned a college degree, but does not complete college for some reason, is still likely to earn more than the average high school graduate.</p>