This topic reminds me a lot of something Dan Rutter used to talk about every now and then.

He observed experts in a field achieve great success in their field and even add new things to that field. They become very specific and specialised, earn a lot of money and get a lot of praise within that field and especially that specialised corner of it.

Then they retire or pick up a hobby and they assume that because they were quite brilliant at something after a decade of study and decades of work in that field that they're just generally brilliant and can pick up high level concepts outside their field easily. Instead they hit the Dunning-Kruger effect, hard, and end up with manifesto conspiracy level theories about things that read like absolute nonsense built on bad assumptions and conjecture to experts in that field.