It turns out there is literally no amount of being publicly right about a longshot bet sufficient for people to conclude you hold your beliefs because you think they are true.

But longshot bettors have it easy. Society quickly forgets all the predictions that don't come true. It remembers the one that did, and treats the prognosticator as a prophet. In social terms, predicting doom is an asymmetrical strategy, because you only have to be right once.

Which is also to say it's a cheap bet that anyone with no reputation can afford. Hence, not believing doomsayers mean what they say is a sort of societal hedge against people flooding the zone with doomsday scenarios about everything.