I've thought about that a lot, and I've always found the question really interesting.
It seems to me that the raw material to master DK (at least to the point of getting a kill screen, or even a million) doesn't seem to be particularly rare. Not, at any rate, anywhere in the same ballpark of rare as Michael Jordan-like talent.
My evidence is that a very large percentage of people who set out with the serious intention of achieving a kill and/or a million at DK eventually succeed. Pretty much everybody who has ever wanted it, got it. I've heard it said, and it's being said more and more often lately, "any idiot can get a kill screen."
I wouldn't put it that way, but I do have to disagree with Walter in KoK when he says that playing at a high level takes "deep, comprehensive intelligence" or even "hardcore skill" as Billy says.
It really just takes "hardcore interest," and a very narrow band of the intelligence spectrum.
In fact, I can really only think of one player who has put a lot of effort into DK that (I'm sadly starting to believe) may genuinely not have the capacity to killscreen it.
This world of ours is super-tiny potatoes. And even within our tiny world we have over 50 kill screeners and are about to crack 20 million-pointers. It's not like basketball or baseball where there are literally tens of thousands of people striving to get into the NBA/MLB-type upper echelons.
There's definitely a "self-selection bias" here that taints all of this analysis (most people who take up the game seriously only do so because they already have an affinity for it), but rest assured, if an internationally-publicized $20,000 bounty for every first-time killscreener had been put up 5 years ago, we'd have thousands of killscreeners by now.
Even if that bounty were on 1.2 million, it would have been claimed, many times over by supergeniuses who the DK world never would have known otherwise. Incentivize something with cash and you'll find out pretty quick how rare the talent needed to do it really is.