That doesn't sound like a particularly educated opinion.
I know it to be patently false because these are people I have regular dealings with all the time. Whether through my own business, at the IoD, at CIMA CPD events, industry gatherings, through events arranged by my banks or auditors, ect. I meet with these people a lot and with very, very few exceptions they are all very intelligent, qualified and capable.
I also employ quite a few people and see them daily. Of the few who ever express the belief that they could do be jobs of their superiors, every single one has been at the bottom end of the IQ range that we employ. Not one had even the first clue about how to approach the role they claimed to be able to perform. None of them could even have approached the role after the years of training and experience those in the roles have.
In my experience there's a clear inverse relationship between intelligence and the belief in one's ability to perform the role of one's superiors.