If enough people are saying the same thing and only one person is disputing it or telling a different story and trying to tell you that everybody else is lying (or spreading "fake news").......then that one person is MOST LIKELY either lying to you or they are bat-shit crazy.
It is called "gaslighting" and Trump is pretty much the poster child for it.
"One lawyer told a story from early in Trump’s presidency of his legal team urging him against tweeting about the Mueller probe, only to find he’d tweeted about it before they got to the end of the West Wing driveway. Several people said Trump was nearly impossible to represent and that it would be unclear if they would ever get paid.