[kirevmaco]

I'm convinced that a large part of this kind of thing is related to personality.

People's ability to get "in the zone" depends on if the level of presentation fits them. I remember in AP Chemistry, some kids just thrived on the rote memorization nature of the whole course. They did great. Some of us found it nonsensical that we had to memorize so much without explanation but we still managed to push through and get good grades. The people who did better weren't "smarter," they just never cared to ask any bigger questions about the material. I'm sure that lack of curiosity helped them to succeed in standard careers.

A person who was "smart enough" to do cutting edge theoretical research might get lucky and have a personality that fits with having a more standard life. Someone who isn't "smart enough" might be very interested in certain problems and push through to finding the answers. Someone who is "smart enough" to do that and doesn't like bureaucracy might drop out of grad school, or even undergrad.