Americans are suckers for suckers.
One of [P.T.] Barnum’s more successful methods of self-promotion was mass publication of his autobiography. Barnum eventually gave up his copyright to allow other printers to sell inexpensive editions. At the end of the 19th century the number of copies printed was second only to the New Testament in North America.
Often referred to as the “Prince of Humbugs,” Barnum saw nothing wrong in entertainers or vendors using hype (or “humbug,” as he termed it) in promotional material, as long as the public was getting value for money.