RE the craving for certainty there are some oddities here.

For example the Pizzagate conspiracy theory was (apparently) widespread but only one guy actually went to the restaurant with a gun. That's one too many, but why only one? Did the others not really 'believe'?

Some conspiracy theorists seem to enjoy throwing wild ideas about and mutually agreeing on them but never actually acting on the 'information'.

Maybe in some cases its a sort of social ritual of mutual assent and not much more?

Maybe they are waiting (advertising?) for a demagogue to come and lead them?