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.
Yep, that's exactly what I came here to say. I was hearing him describe the Dunning-Kruger effect. It's like we have three classes of investors: As, Bs, and Cs.
Investor A thinks he's a B. B thinks he's a C. And the C think's he's an A.
You might think this is only a problem for the C. But it's actually a problem for all three of them. They're all failing to estimate their own ability and it negatively affects the outcome.
I like to think I am less susceptible to the Dunning-Kruger effect because I am not hyper-intelligent or extremely unintelligent. Maybe that is just a manifestation of the effect! Maybe it is not? Damn. See what I mean?
Also, it seems reasonable that certain people (perhaps myself included, although that is not altogether self-evident) may be technically capable of "mastering" a domain, but also understand their own limitations and therefore choose not to spend their limited mental capital on that domain while still participating in it at a lower level simply to increase the list of trades they are a jack of in order to be able to come closer to mastering another trade, or at least being a better jack at a particular trade. Wow, what a sentence.
Finally, as relates to almost completely off topic, that this post could be rewritten replacing investing with philosophy, theology, politics, etc., and that it would be prudent for those that agree with the assumptions of the article to apply them to these parts of their lives as well.
I have for quite some time been part of the sheep mentality to crypto (being new to this space), but finally have found the benefit of doing my own research. In fact for the first time this has shown in the (slow) growth of the value of my portfolio.
However I have certainly found that in forums certainly individuals match precisely the definition you provide. To someone like me, this is perceived as arrogance and I have to resist the urge to go back to old posts and point this out when their decisions/advice has been shown to be flawed or totally wrong.
This certainly is even more true in the crypto world where in the short term, peoples emotions seem to dictate price as opposed to well thought out technical analysis (this of course is a generalization).
I've been trying to google up one of his articles that includes it but am having no luck. He had a snappy name for it like Engineer's Dementia.