Probably has an extremely sound understanding of accounting, basic finance at a undergrad level, and probability and statistics too..basically like an actuary with a solid understanding of business.
My guess is to why he is successful is that he basically was great with people (a salesman), really interested in the topics above since he knew that was how to read financial reports, and also extremely lucky to be born in the time and place he was. Don't forget, his father was a congressman.
