Warren Buffett, the chairman of Berkshire Hathaway (BRK.A), is the most successful investor of our time. His daughter, Susan, worked as my assistant when I was the publisher of a magazine 40 years ago. Just before she got married, Susie told me she worried that her fiancé’s parents had bought a couple of shares of Berkshire stock — and what if it tanked? At the time, the price was about $1,000 a share. Today, it’s $507,000 a share. I hope the in-laws hung on.