I think that's an unfair characterisation, I doubt most people making the statement are arguing that people are stupid, but more often that they have been lied

I think that's an unfair characterisation, I doubt most people making the statement are arguing that people are stupid, but more often that they have been lied to/duped by people seeking to use their support for policies they might otherwise disagree with or vice versa. E.g. people who rail against Obamacare in one sentence and praise the affordable care act in the next are not inherently stupid, they have more likely just been repeatedly lied to/misled