Nope, complete luck. One Tik Tok influencer with tons of followers did a 30 second video and that was all it took. Before that the book wasn't selling at all. And it is really terrible writing. So many of these just come down to the writer lucking out and finding an audience. I'm not sure marketing really makes a big difference. If there really was a method that worked then the big publishers would have started using it a very long time ago and they would always put out best sellers or at least books that make a profit. which isn't the case by a long shot.