(I find my earlier comment rather harsh and brash, so allow me try again.)
Search as you will, every statistics or metric of the Civ playing base, you'll not find a single one where majority of the players play at the highest level. Civ is a difficult game, and vast majority of us play at a level far below Diety. That's just the nature of Civ - it's a very hard franchise.
I'm not trying to say that your playing level somehow equates to intelligence, but the opposite. Yet suppose the null hypothesis from the topic is true, then what does that fact, that there're very few "tommynt" level savant players among us say about rest of us?
It may very well be that the top level, most competitive players among us exude certain brilliance that we call "smartness," would they shone with other games? I would say so. In the past I was quite active in the StarCraft scene, and tommynt reminds me of those sort of natural talents that elsewhere can earn a living playing video games. His talents could easily shone in StarCraft or chess or scrabble instead. He just so happen to be playing Civ, and sometimes hand down a bit of tips and tricks to us mere mortals.
So what does that leave the rest of us, if we do not (1) play competitively nor (2) exhibit any natural abilities? Are we playing civ smartly? Are there any evidence of our "smartness" for wasting time in this game versus that?
I find it hard to believe that's the case, that somehow by picking up Civ5 instead of Black Ops 2 at Game Stop I suddenly elevates my station. Surely, I won't be putting "Play BnW on Immortal" on my college app.
It's silly, to think playing a game somehow make you or I or anyone inherently better. People play game to lull away time. We play Civ5 because we find it fun. That's all there's to it.