Earlier quoted context omitted.
I suspect that even his proponents knew better, they just didn't care as much about the economy as they did culture wars nonsense and religious woo-woo.
I think a large number of people don't "believe" things in the same way that the typical commenter here would understand it. Your average rationalist techie would consider a "belief" to be some factual statement about the world, backed up with some justification, with some confidence level. "Tariffs help the economy" would mean some probabilities about likely outcomes for different actions, based on some kind of econ…
So is the theory that they don't say it because they actually believe it, they say it because they want YOU to believe it? Or is it that they believe it just because they wish it were true?