Editor's note: This column was co-authored by Stephen Moore. We are going to reveal the grand secret to getting rich by investing. It's a simple formula that has worked for Warren Buffett, Carl Icahn and all the greatest investment gurus over the years. Ready? Buy low, sell high. It turns out that Donald Trump has been very, very good at buying low and selling high, and it helps account for his amazing business success. But now Hillary Clinton seems to think it's a crime. Campaigning in California last week she wailed that Trump “actually said he was hoping for the...