I'm not sure what you mean by "those people", but the actual cutoff where you start having problems with people being extremely bored comes well before you hit one in a million; it's closer to one in a thousand, in my experience.

Which means that the NYC public schools (the subject of this conversation, recall) have ~1000 kids like that right now.

Now their various "gifted" programs do take more kids than that; the bar for such things is often at the 95th percentile, not the 99.9th.