I think we agree completely that the use of GPA as a measure of ability is limited. To be fair, though, I never asserted that GPA would predict who would 'have a better social life' or who would be 'in better shape.' In fact, I might predict that these would be negatively correlated with GPA. Also, I'm not sure I understand your story: did your friend actually have low grades, or are you just saying he was highly successful after attending a less famous school?

In any case, I hesitate to offer my own examples: I don't have a sufficiently large sample size, as I don't hang out with people who had low GPAs.