How do I know what?
That L. Ron Hubbard devised Dianetics in a little more than a day. This was common knowledge in the LA sci-fi social groups, particularly the Los Angeles Science Fantasy Society and one of its founders is Mr. Sci-Fi, Forrest J. Ackerman, who was and still is a close friend. Hubbard attended many meetings of LASFS. John W. Campbell, the editor of the then Astounding Science Fiction (now Analog) finally confirmed this. He was the first to publish the "process" within the pages of his magazine. Later, it was just an embarassment.
Ayn Rand devised "objectivism" in a few days for the novel "The Fountainhead." After the publication of "Atlas Shrugged," it began to be an actual movement and is now not as large as Scientology and, thankfully, does not have all the screwy ideas about the influence of alien's from space. Rand eventually went off track and devised a religion based on pantheism.