Yesterday, I wrote about five rules for successful growth investing, but perhaps the biggest rule of all, which has existed for centuries, is about diversification. “Never put all your eggs in one basket.” Of course, everybody knows this, so I don’t even include it my five top rules. But sometimes … people forget. Which brings me to Bernie Madoff, who now sits in jail while the SEC moves down the ladder of responsibility at his firm. For weeks, we’ve heard sob stories about his victims, most prominently those who invested their millions only with Bernie, and, in the great...