I considered the existence of Santa a definitive proof that the paranormal/magic exists and not everything in the world is in the domain of science (and was slightly puzzled that the adults don't see it that way).

No conspiracies, but for a long time I've been very prone to wishful thinking. I'm not really sure if believing in Santa actually influenced that. I don't remember finding out the truth as a big revelation, though - no influence on my worldview or on trust for my parents.

(I've been raised without religion.)