"A Face In the Crowd"
A depraved, Trump-like populist politician, played by young Andy Griffith, swindles followers and treats women like crap. At the end, a brave young woman causes him to be heard on the radio trashing the naivete of his dumb supporters and they all stop supporting him in a fury.
That movie anticipated many things about this era, but not the ending where the supporters see who he really is and still storm the Capitol for him.