The day before he beat the greatest chess player in the world, Hans Niemann was a curly-haired 19-year-old American known only to serious fans of the game and mostly as an abrasive jerk. Everyone, it seems, has a story. Like that time in June, when he’d lost in the finals of a tournament in Prague, then stood in the ballroom of the hotel where the event was held and ranted against the city and the accommodations.