Like it or not, the Kardashians have risen from reality-TV stars — famed for sex tapes, plastic surgery and shotgun weddings — to America’s royal family. Critics have discounted the clan as an unfortunate blip on our cultural radar. But the ladies have taken their 15 minutes of fame and created a dynasty that might just be the most powerful in the world. In May, Kim successfully lobbied President Trump to commute the prison sentence of a 63-year-old grandmother, Alice Marie Johnson, who had served more than 20 years on drug charges. Kylie, meanwhile, single-handedly tanked Snapchat’s stock in February...