LAS VEGAS — The last time Conor McGregor was in a UFC cage, he was merely the biggest star in the history of mixed martial arts. In the 23 months since, the loquacious Irishman has become exponentially richer and much more famous. With his boxing loss to Floyd Mayweather as the catalyst, McGregor has ascended to a new level of stardom and success outside MMA and outside sports. Even UFC President Dana White wondered whether McGregor (21-3) would decide to fight on, but he did. McGregor returns to the octagon at UFC 229 on Saturday night to fight lightweight champion Khabib Nurmagomedov (26-0) in a Las Vegas arena full of boisterous Irish fans.