We can always use more case studies of insanity that aren't religion, right?
Well, Miracle Mineral Supplement is my new go-to example for Bad Things happening to people with low epistemic standards. "MMS" is a supposed cure for everything ranging from the common cold to HIV to cancer. I just saw it recommended in another Facebook thread to someone who was worried about malaria symptoms.
It's industrial-strength bleach. Literally just bleach. Usually drunk, sometimes injected, and yes, it often kills you. It is every bit as bad as it sounds if not worse.
This is beyond Poe's Law. Medieval blood draining via leeches was far more of an excusable error than this, they had far less evidence it was a bad idea. I think if I was trying to guess what was the dumbest alternative medicine on the planet, I still would not have guessed this low. My brain is still not pessimistic enough about human stupidity.
People sometimes seem to use a model that says that potency is a scalar quantity. If you have a powerful illness, you need a powerful medicine to defeat it. Weak medicine has little side effects; powerful medicine has big side effects. So if something has big side effects, that means you know it is powerful medicine!
People use a similar model for computer security: Installing antivirus, a firewall, or other security features gives your computer some number of security points. Like armor class in D&D, the more security points you have, the harder it is for an attacker or malware to hurt you. If you install a lot of security stuff, it will make you really safe ... and you can safely go do dangerous things like installing software that fell off the back of a truck, or browsing spammy porn sites with IE6.
The problem in both cases is an ignorance of how the attacks work, and thus how the defenses have to work, too. An arbitrary chemical that has heavy "side effects" is not thereby a potent remedy for infections, cancer, wounds, and other diverse afflictions. Malware and attackers use specific exploits and tricks; in order to make your computer safe from a specific attack, security software has to block particular things.
And unlike in classic D&D, putting on a helmet doesn't make it any harder to run you through with a lance.