Would you like a windfall of free money? Just download an app and start betting on sports. It’s easy, it’s fun, and it’s cool. Don’t miss out! That was the pitch in several ads during the Super Bowl this week, as legal gambling companies sought to entice a few million additional Americans into the fantasy of hitting it big. “Life’s a gamble!” said DraftKings’ new mascot, the Goddess of Fortune, as she invited fans to be as daring as Evel Knievel and Joe Namath. Not long ago, the NFL, the NBA, and Major League Baseball all insisted that widespread legalized betting on their sports could, as NFL commissioner Roger Goodell put it, lead to “the fixing of games”—another Black Sox scandal. But after 30 states legalized sports betting, the pro…