No, not really "enough said". If a correlation is demonstrated between two events, then the probability of the observations being due to chance is low. Now, whether we conclude that "A caused B", "B caused A" or "something else altogether caused both A and B" is another matter. In this case, since the MBA likely precedes billionareship, we will rule out the possibility that the MBA was caused by the billions. As to which of the remaining two explanations is the case, I suspect that it is a mixture of the two.