Credulousness / Gullibility
Yes, stupidity is required here, but keep in mind that the MAGA crowd will believe anything, regardless of how absurd, if it comes out of Donald Trump’s mouth. That’s more than mere stupidity.
Someone asked me recently if I thought it was possible that Greenland holds a legitimate national security purpose for the United States (as Trump claims). I responded that I don’t know, because I’m not privy to our military secrets, but I’m 100% confident that Denmark will allow us to do anything we want on Greenland if it will help protect the world against foreign aggression.