L. Ron Hubbard roughed out the story that became Scientology’s equivalent of the Garden of Eden narrative: how evil came to the Earth, and what we have to do to become pure. Read about it here.
Xenu, the Head of the Galactic Confederation, solved a massive overpopulation problem on his 75 planets some 95 million years ago by bringing people to Earth, putting them in volcanoes, and detonating H Bombs in the volcanoes. (How very 1950s!) This has emotionally scarred us (even if don’t remember it) throughout all our subsequent reincarnations, and only by remembering the details (including time and place) of traumatic events (including in past lives) can we cleanse ourselves of the trauma and return to being spiritual creatures who can control the physical world around us…
Other traumatic experiences, according to this page on The Beliefs and Teachings of Scientology, include “attempted abortions and other fetal traumas, acts of torture and violence experienced both as victim and as perpetrator, encounters with the Marcab Confederacy and various Invader Forces from spacefaring Galactic civilizations, life on earth as a clam,” etc.
Your past goes back billions of years. The cost of having Scientology help you clean it up, all the way back to the clams, may well be $500,000 or so.