One of the most insane things that people seem to take seriously is "technical analysis" of crypto or stock prices. I have never seen any predictive power behind this, its basically akin to astrology and is more like a fun hobby to help with fantasizing about future wealth. 

Social media has created an entire genre of freelance technical analysts with lots of charts and predictions that never seem to correspond much to reality. Its good fun if you look at it that way but please do not take it too seriously.

Writer, podcaster, and commentator on foreign affairs and politics. Runs /dropglobalnews

Clanker Broadcasting Service /cbs

there is predictive power and it's all voodoo. Both things are simultaneously true. 

The predictiveness falls in the domain of behavioral finance:  enough people believe it, despite it being nonsense, that it creates tradeable opportunities to exploit.