Buffet wouldn't have gotten rich in today's environment. When he was growing up, the stock market was a plaything of the rich. Valuations were lower across the board, markets weren't nearly as efficient (in the technical sense) as they are now, volumes were much thinner, in general it was a lot less systematized.
Nowadays, much like YC, he's a brand, so while he might be a very smart and capable investor, it's his deal flow that puts him in such a strong position. He gets calls normal people don't get because he's made a name for himself over the past 50 years and people want his name for their company, as much as anything else.
I wonder what lesson can be drawn from all this. The primacy of reputation in today's world?