I think it's a natural consequence of being really smart and knowing a lot about some field. If you know a lot about some field, you become extremely aware bot

I think it's a natural consequence of being really smart and knowing a lot about some field. If you know a lot about some field, you become extremely aware both of all the things that you don't know that you wish you knew about that field. If you're really smart you probably affiliate with a lot of other people who are really smart. You also have a sense of how much these smart folks know that you can barely fathom. It's not an ironclad relationship, of course, but an awful lot of the smartest people I know are humbler than an awful lot of the idiots that I know, and that's my current working hypothesis as to why.