Which part - that making money is not equivalent to creating value, or the specific example of teachers creating more value than MBA's?

The latter.

I guess you're right that it isn't cut-and-dry, but my hypothesis would be that a great X-er can most of the time inspire children to be great X-ers themselves. Hence, whatever she would accomplish on her own, she can accomplish tenfold by inspiring her students.

What about "teach by example"?