He wasn't as smart as he thought he was.
No doubt!
I found this claim elsewhere on the internet. Again, with no evidence. I would like to have this verified:
He went to the University of Cincinnati from Fall, 1911 through the Winter, 1913, completed 36 classes with 23 A's, 8 B's and 5 C's. He only took one class in Ancient Greek and a few other classes in Classical Greek.