For most of Donald Trump’s brief political career, chaos has been his friend. He draws energy from an endless storm of difficulties and controversies that would send most presidents into the fetal position. Critics and supporters alike compare his presidency to a reality television show, one that always ends with the leading man getting the last word. From Russia, Russia, Russia to Ukraine and impeachment, Trump’s time in the White House has been a continuing roller-coaster ride between danger on one side and disaster on the other. A political Houdini, he has always escaped and emerged stronger in victory, but...