Violence (including mass shootings and church burnings) inspired by replacement theory and incelism.

Anti-vax beliefs led to more deaths due to COVID, and greater economic and systemic stress than otherwise would have occurred had a significant number of people afraid of adrenochrome harvesting and the New World Order not purposely undermined pandemic control efforts.

Currently the "groomer" conspiracy theories seem to be headed towards some mass cultural violence event towards trangender people, with politicians openly calling for the "elimination" of transgerism, but that remains to be seen.

But let's ask what atrocities have ever been prevented by conspiracy theories? None. QAnon has been more of a hindrance to efforts to combat child abuse and human trafficking than a benefit, and they were entirely focused on "decoding" the Podesta emails and "exposing" satanic rituals in the Democratic Party while Epstein was going about his business.

It should go without saying that none of the doomsday scenarios the COVID conspiracy theorists predicted came to pass. All they accomplished was making the pandemic worse. And no doubt the seeds of paranoia and mistrust they laid will make the next pandemic worse as well.

Hell, even MKUltra wasn't uncovered by conspiracy theorists - it was exposed by accident through an unrelated FOIA leak. NSA spying? The Simpsons did a bit about that before Snowden, but conspiracy theorists were going on about mind-control rays being beamed through televisions and mass hypnosis.

These people want the world to believe they are the the ones constantly telling truth to power, the only ones who can see the dark truths hidden behind the curtain, and they'll insist they are always right. But at best they only coincidentally appear to be right, in the same way as a stopped clock, and always in a way that does more harm than good.