Nobody is more stunned about the stratospheric sales of “Fire and Fury” than the guy who wrote it.Michael Wolff and I were talking backstage prior to his gig on Tuesday night at the Free Library of Philadelphia, and he confessed that he never saw it coming. He was convinced that he’d gotten the inside skinny about Trump’s den of dysfunction, but in our info-saturated ecosystem, with Trump under scrutiny 24/7, who could have envisioned 11 printings within 12 days of release?The best explanation is also the simplest: Trump confirms the book on a daily basis.After hanging out in the West Wing for nine months (“I was let in without anyone weighing the meaning or consequence of what I was going to do,” he said on stage last night) - Wolff concluded in his book that Trump is dangerous, incompetent, ignorant, and unfit to serve.“Everyone, in his or her own way, struggled to express the baldly obvious fact that the president did not know enough, did not know what he didn’t know, did not particularly care, and, to boot, was confident if not serene in his unquestioned certitudes,” Wolff said. “I was just the guy listening, occasionally nodding my head as if in agreement, and over time, they poured their hearts out.”