What's going on here is a sort of reversal of judgment; cranks start with the conclusion of "I am a genius" and construct their whole reality around that assumption, working backwards to the magnificent and triumphant "theory" that justifies it. Pretty much anything contradicting that conclusion cannot be part of that reality, so it doesn't exist for them. In other words, it's really just narcissism, with a bit of schizophrenia thrown in, corresponding to the stubborn and crazy axes. The naïve ones aren't really in the same category; they have a little fantasy in their heads, but once they learn about how science actually works, they immediately realize that they are way out of their element and cease speculating.
When I was a kid, I had similarly grandiose dreams. Which is normal. There wasn't all THAT much difference between myself and a crank at the time, except I didn't confuse fantasy with reality, and outgrew it in short order. The cranks suffer arrested development to a degree that their fantasy pushes reality off the stage.
And yeah, they are ALWAYS engineers.
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