Norb Vonnegut culls three lessons from HBO's recent Bernie Madoff biopic. Taken together, they serve as a renewed prompt for investors to consider low-cost index funds. After all, these funds are hardly exclusive. The world is vetting them constantly. So long as investors reinvest dividends and other cash flows back into the funds, the annualized returns are a real measure of investment performance: What you see is what you get. And what’s better than that?