Let's not forget W. He was denied admittance to UT's business school based on poor academic performance but got into Yale. I wonder how that happened?
And Nash, that is an impressive list but very much the exception to the rule. Education and grades are very much an indicator of intelligence, which in turn is a very likely precursor to success. Take a look, for example, at NBA owners. Very much a billionaire's club. I believe they are all college graduates (I researched this for another issue not long ago), and over half were Ivy League educated.