We listen to a lot of things. The more improbable and outlandish they are, the more likely they will stick in the ear-canal. Alt-facts are crafted to seem like they are real; they have just enough of the “no, really, you don’t say” to titillate.
Rumors start because they seem to have an element of certiude. Often they can be backed up by facts, or the appearance of truths.
For instance, I heard that the Falcons won the super bowl. The announcer said that no team came back from a greater than 10-point deficit in any super bowl game. That’s 50 years of history, folks, and Atlanta was leading 21 to nothing when I changed channels.
My personal alternative fact for Super Bowl LI stands. Spread the word.