I too have shiny names on my resume and barely managed to float. A few classmates sat around one day and decided to use a calculator to find our average IQ and it was over 140.
I did find, later on, my “small pond” or niche. What Malcolm Gladwell misses is that, in the long run, the bottom feeders do come around and have successful lives afterward. It may not be what they have imagined going into top programs but they do find their niche, they don’t just disappear into oblivion.