A debatably wise man once said that the best-seller was a gilded tomb for a mediocre talent. As with all easy aphorisms, it’s only 90 percent true. 
 
The riddle is solved one of two ways: either the writer of the best-seller stumbled blindly upon a winning formula that one time only, or the writer always knew what they were doing and some combination of chance and synergy caused that one book to take flight.