At the 29:45 minute mark of the above video, during a long passage of boasting about his accomplishments and assets, Trump brought up his 1987 book The Art of the Deal.

“We had great success in the book world. The Art of the Deal, one of the most successful books ever done…in business. Maybe the most successful. See, I used to say the most successful business book ever written. But I don’t do that now.” Trump then points at the media pit in the back of the room and affects a simpering, mocking tone. “Because they’ll go back and examine. ‘Well, let’s see, twenty years ago somebody wrote a book,’ let me just tell you. So I say one of the most successful, but I think it might be the most successful.”

Trump actually takes time out from his hyperbolic bragging to berate the media in an insulting and puerile mocking tone for doing their job. What else is the media for except to fact check? He even admits that they’re right, that he began saying “one of the most successful books” instead of the “the most successful.” Trump shows so much contempt for the truth that he can’t even be bothered to fact check himself and see if his book is the best selling business book of all time. It took me 15 seconds to find a comparison of The Art of the Deal against other business books.

Successful? Yes. Even one of the most successful? Yes, it’s hard to argue with that, The Art of the Deal made the top seven. But “most successful?” Definitely not. Estimates on The Seven Habits of Highly Effective People range as high as 25 million copies sold, whereas The Art of the Deal sold in the neighborhood of 1 million copies. Mocking the media for fact checking your inaccuracies will not help you sell more books.

Sources:
Video: https://www.youtube.com/watch?v=cXqJXbtOs9Q
http://www.politifact.com/truth-o-meter/statements/2015/jul/06/donald-trump/donald-trumps-art-deal-best-selling-business-book-/
http://www.inc.com/bill-murphy-jr/7-incredibly-successful-business-books-where-s-donald-trump-on-the-list.html