You literally can’t argue with them, though @alms, that’s the problem. I mean, have you ever tried arguing with a serious conspiracy theories nutjar who has one of the more out-there beliefs? Especially a complex, impacted belief. I have. I spent a good part of my misspent youth talking to nutters on the internet because they fascinated me.
It’s perfectly possible to argue or even politely discuss people who have extremely different political or religious views to you, so long as they realize those are political or religious. For example, I’ve discussed stuff perfectly well and with mutual regard with people who were extremist libertarians, serious Catholics, and so on. I might not have thought their ideas had any merit, but they were clearly based in the same physical reality as me.
Equally minor conspiracies theories which could potentially be proven/disproven, but for which no-one has clear evidence, like “The US government has evidence of aliens and/or own actual UFOs”, you can often discuss rationally, because the people who believe it tend to accept they don’t have evidence yet, and it’s a belief, and you can perhaps discuss which weird events might be “really UFOs” or which have actual explanations or the like.
But there once conspiracy theories of a serious kind get into the mix, this breaks down, often because the person is utterly insistent on some completely disturbed point which their entirely reality depends from, like that the lizard-people are running the world and any evidence to the contrary is fake lizard-people trickster-stuff. You can often quite easily demonstrate some specific thing isn’t “lizard people”, like you can point to some claim and show how it’s obviously false. If you did that to the libertarian or the Catholic or even the UFO guy, they’d engage with it rationally, and perhaps accept that this was an issue, or add nuance to it. With the conspiracy theorist, they simply double-down. They have a whole giant array of “alternative facts” to draw from, as well as information that people trying to “disprove” these facts are agents of the lizard-people/Jews/illuminati/whoever is FOTM. Groups like flat-earthers exist on the borderline here but are increasingly crossing it to the insane side. Flat-earthers 20 years ago included a lot of people who “had a theory” but weren’t hugely certain, in fact that seemed to be the majority. Nowadays, if you are a flat-earther and are willing to accept that, say, a trip to space might disprove your views, you’re typically seen as some kind of traitor or “not really” a flat-earther. Irrational and absolutely belief is encouraged, or even demanded by this more extreme subset of conspiracies theories. QAnon is absolutely this type. It’s hugely layered in terms of insane bullshit, and they’re told that people who keep disagreeing with them or trying to prove them wrong are part of the “bad guys”. You literally can’t argue with them, because if they don’t quickly win you round, they other you, and dismiss your arguments, and dismiss basic elements of demonstrable reality.
I know you’re trying to take a more philosophical approach here, but I feel like it’s one based in a certain naivete and ill-aimed good faith rather than one based in a reality of having tried to talk to such people.