Some woman’s cat was hiding in her basement. She automatically assumed her Haitian neighbors stole her cat and made some comment about it, which landed on Facebook, which got morphed into “immigrants eating pets” story, JD Vance picked it up, Trump mentioned it in a national debate watched by 65 million people. All of this happened in a few days. This resulted in violence in Springfield.

If you can place a rumor or lie in front of the right person/people to amplify, it will be amplified. It will spread like wildfire, and by the time it is fact checked, it will have done at least some damage.