I think "cult" is the exact dynamic at play here. As much as I love the internet, it has enabled distributed cults on a level rarely seen before. Not only does it support traditional cults with central leaders and official dogmas (which I think includes most MLMs), but they've allowed for a sort of emergent, leaderless cult based on collective creation of the memes that drive it. E.g., QAnon and the cryptocurrency bubble.

And cults can be very persistent, even in the face of spectacular failure! The Great Disappointment predates the US Civil War, but it spawned at least one group that is still going today: https://en.wikipedia.org/wiki/Great_Disappointment