You're dealing with a lot of silly people in the marketplace; it's like a great big casino and everyone else is boozing. If you can stick with Pepsi, you should be O.K.
Source, in full
On being dispassionate and patient in investments, in an interview in Forbes magazine (1 November 1974); he is contrasting soft-drinks to intoxicating beverages in this example; Buffett eventually became a major investor in Coca-Cola.