Someone that is intelligent in one area can be ignorant in another so fooling people can just be a matter of subject area.
Also a con man can convince an individual at first but for it to be reinforcing there needs to be a community of people that are reinforcing the ideas and in that process build ontop of what the con man introduced.
If it requires alot of domain knowledge and skill why not?
Would you say that they at least can be smart in other areas though. Like personal hobbies that they have?
Your point about choosing to trust people/organizations selectively is a good insight because to do that you have to have reasons on why you can trust instead of blindly trusting in certain sources (which is what authority in practice makes people do). Part of critical thinking actually helps with that. It is just that critical thinking isn't at the forefront of what we teach people or even how we communicate with others.
Edit: Also sometimes they don't trust that information so they won't change their beliefs just because you present them with the correct information.
I like how you went into more detail about how to break these patterns. Which is starting with what they already believe and showing the contradictions. I gave you an upvote.
I agree that it is easier to engage with someone if they aren't shouting you down all the time but sometimes that attitude in and of itself can come from beliefs that individual has. For example if a person is christian and they believe that all gay people are choosing to be sinners therefore they are choosing to be bad then it makes sense that they would act more hostile to people that are gay.
That behaviour isn't justifiable and shouldn't be accepted but that is also a tactic that gurus/influencers can use to isolate the people in those groups. You convince them of something that makes them act hostile towards a specific group in turn isolating them even more.
And as for the scientfic model yes it is true that there are axioms that we put our trust in but it isn't done unreasonably. A key idea in science is to trust but verify. This means that you can be concious in who you trust in and it is never absolute.
If I were to simplify it I'd say people aren't stupid just because they have incorrect beliefs. Even the incorrect beliefs that people do have tend to have internally coherent reasoning.
Sorry if it that's what it comes across as. I just like crossposting to different communities because the fediverse is pretty separated so I'm not sure that people are in the same communities.