I would say they’re often no more interesting than anyone else.

My sister-in-law supposedly believes Princess Diana was assassinated, which is included in one of these lists of popular conspiracy theories. She might have other similar beliefs, but as far as I know, she’s a normal person with fairly normal (uncontroversial) beliefs.

To me, a single belief in A conspiracy theory is not that big of a deal. When someone starts believing in many of these, it gets more interesting.