In 1987, McDonald’s launched an ingenious sweepstakes based on the game of Monopoly. Customers would purchase sandwiches, fries, drinks, etc., that included peel-off game pieces on the packaging — potentially rewarding them with anything from a Filet-O-Fish to a new car to $1 million. People went wild for it and business spiked by 40 percent for the fast-food giant, which kept it up for years. But it wasn’t all happy meals. “It seemed like an opportunity for ordinary people to get ahead, but there were consequences,” said Brian Lazarte, co-director of the HBO docu-series “McMillion$,” premiering Monday, about the contest. In fact,...