The really important idea here is that not everything can become the subject of conspiracy theories, chairs, friends, or plain money f.e., even when there is an effort.
I 100% disagree with that. Money especially has been the subject of countless conspiracy theories. There are plenty of people (for example, with schizophrenia) who form conspiracy theories about their friends. I'm not sure there's ever been a conspiracy theory about chairs, but that's only because there's never been a sociological reason for there to be.
You are treating ideas that exist only in particular times and cultures as inherent things that will naturally arise out of the existence of particular physical objects. That's nonsense. Those ideas come from culture and social relations. In a culture that has the memory of life before vaccines within living memory, conspiracies about them don't tend to emerge or gain traction, even though the physical object is the same. I feel like I'm repeating myself here, but that should just be the end of the discussion. It's clear proof that it's cultural and sociological.
Let me just put it this way: Is there any conceivable evidence that could exist that would falsify this idea that conspiracy theories come from the properties of particular physical objects rather than sociological factors?