As cable television broadcast the scenes of Trump supporters breaking past police lines and even smashing their way into the Capitol on January 6, the president’s son, Donald Trump Jr., texted Mark Meadows, the White House chief of staff: “He’s got to condemn this sh** ASAP. The Capitol Police tweet is not enough.” A little later, Don Jr. texted again: “We need an Oval office address. He [then-president Trump] has to lead now. It has gone too far and gotten out of hand.” It’s that last statement that reveals the whole truth of January 6 for Trump’s supporters. Donald Trump’s...