[Question] What weird beliefs do you have?

We know that mainstream thinking gets a lot of things wrong. Many of us have experienced being mocked because of our concern for AI extinction-risk. There are plenty of other examples of times where now well-evidenced beliefs were seen as crazy in some way. This post was prompted by my reading around meditation and mindfulness—twenty years ago if you said that meditation had a number of mental and even physical health benefits and was worth practicing for non-religious reasons, then you would be laughed at as a New Age type who probably believed in crystal healing and astrology too. Now there’s stacks of scientific evidence supporting that view.

I would like to keep an open mind and not dismiss fact-claims just because they pattern-match to weird people or because they don’t pass the absurdity heuristic. On the other hand, there are a lot of crazy people out there and I don’t really want to wade through dumb stuff by flat-earth types. So I figured posting this question here is a good way to find some interesting ideas. Fellow Rationalists, what beliefs do you have that would cause the average member of society to laugh at you or call you weird?

I have at least one such belief, but I’ll post it as an answer to this question, because I want the focus to be on the question and not on my specific belief.

Edited to add: please include a summary of why you believe what you do—what evidence or chain of reasoning led you to this belief?