are players ever just "not smart enough" to move up?

[ski]

I've been playing mid stakes basically professionally for about a year now.

I read aba's pot about how he basically moved from 200NL to 10K NL in the matter of like 1/2 a year.

I'm wondering what stops players from moving up? Are they not studying correctly? Are they incapable of thinking on the levels that people playing higher stakes play? For you guys that are overrolled for your levels, why don't you move up? Do you feel like you have gotten into a rut and are having a hard time understanding the different thinking at different levels?

I personally have the bankroll for 2000NL but feel I'd get destroyed there and play 400 and 600NL primarily. If it even matters I have a low level genius IQ, but still feel I get genuinely outplayed a lot even at 600NL

PS I have absolutely no clue which forum to post this in..