I think in there would be the difference. I agree that they're not necessarily stupid or anything but, as im sure you're well aware, a good part of higher education is about comparing, contrasting, critiquing sources of information and compiling that into something to be marked by someone who has shown a sufficient skill in being able to to that aswell.

So, in general terms and not necessarily OPs cousin, I think uneducated is part of it and it does seem to the a recurring theme in the conspiracy type. I think it has to come with being at least just smart enough to be dangerous, often smarter, but also a with kind of arrogance and narcissism to convince themselves they know better about all these very in-depth subjects than virtually all the experts.

Although, some of them full on know its not true. The trouble is, theyre too far into the "big lie" now. So much of their personality is caught up in it, they could never back down, no matter what.