Ah, Manson. The ultimate Family man. He was right about the likelihood of a racial rebellion across the United States, but wrong (as yet) that whites would annihilate each other in the ensuing struggle and leave the Manson Family to rule the remainder of humanity from their hidden city beneath Death Valley.
This has been another edition of Good Deduction, Bad Deduction.
The truth of the matter is that many people often have insights into the course of our civilization, and others stumble into their prognostications by sheer chance, with the result being that there are plenty of people who have predictions for the future that time will uphold. It's not limited to brainwashing cultists.