People see some stupid anecdote and then share the theory that fits whatever they believe to be true no matter how nonsensical it is.
If I told you the people on the north side of my grandma’s nursing home died before the people who lived on the south side, you’d have some theory about sunlight exposure and excessive mold growth on the north side of the building. Air pollution kills!
But then it turns out the north side is just where they put the sicker people.