Ah, yes, the descent into epistemological nihilism. "Can we really know anything for sure, man?" That was pretty fast, actually, it usually takes longer than half an hour.

Anyway, that's a great example of the kind of thing that, indeed, makes conspiracy theories very hard to debunk: at this point you've practically admitted you're not interested in reason. That's why it's not worth it to try. Hence, the existence of the downvote button.