Since the data points are solely about extreme wealth and Elite MBAs, the only thing that can be proven is some degree of correlation between the two. What you have is insufficient (by a lot) to prove causation.
If your thesis is that the Elite MBA led to the extreme wealth, you have to look at the volumes of Elite MBAs out there. HBS alone turns out 1000 a year. Only a small % of them get to extreme wealth (going back to your point that a few hundred million doesn't count).
As someone else noted, an Elite MBA is a worthwhile investment as a stamp of approval. I have one of these, and I can speak from experience that it helps. Is it going to get me to extreme wealth? No.
If your thesis is that the Elite MBA led to the extreme wealth, you have to look at the volumes of Elite MBAs out there. HBS alone turns out 1000 a year. Only a small % of them get to extreme wealth (going back to your point that a few hundred million doesn't count).
As someone else noted, an Elite MBA is a worthwhile investment as a stamp of approval. I have one of these, and I can speak from experience that it helps. Is it going to get me to extreme wealth? No.