The oldest and strongest emotion is fear, and the oldest and strongest kind of fear is fear of the unknown.
—H. P. Lovecraft
Warren Buffett and Peter Lynch created massive financial dynasties by following the mantra of “invest in what you know.” Buffett has amassed a personal net worth of more than $60 billion by admitting that he doesn’t buy companies whose products or services he doesn’t understand. In 1999, he told Fortune magazine that “I don’t understand technology.”1 Buffett continues to buy companies whose businesses he does understand—like See’s Candies, GEICO Insurance, Dairy Queen, Fruit of the Loom, and the Burlington Northern Railroad.
Between the years 1977 and ...