conspiracy theories are perfect for certain types of people to latch on to because the narrative presented is malleable. If the theory is wrong it can be re-shaped into something new to explain the new unknown.
if you scrutinised a conspiracy then yes they would generally fall flat, but if someone were the dispenser of that knowledge who imbued themselves with the self-importance of knowing secret details, they could always shift the goalposts and weave a new version of the story to maintain the reality they want to revel in.
you might be referring to the CSI Effect