I guess that a list of college dropouts that are plain losers would be several orders longer. Don't forget about the survivorship bias (http://en.wikipedia.org/wiki/Survivorship_bias).
The one thing to be aware of here is that they didn't drop out of college, because they didn't succeed in it. They dropped out because it was too easy for them.
Good to look at both data sets, but it is possible there is no correlation to being a billionaire and going to college - no way to tell without a constrained environment as there are a billion variables (wealth of the parents, grades in school, etc).