To get really good at Scrabble, you have to grind at it.
Sure, you can do that. Requirements are simple. As Chanda Chisala says, you only need a dictionary. You don’t need a gaming PC or good Internet (or any Internet). And malnutrition impinges least on precisely verbal IQ, which is convenient. As is having a billion people.
But what’s the point, when you have many other other interesting opportunities to gain money, status, or just enjoy life at its own pace?
The highest density of chess grandmasters is to be found in the Balkans. They, and East Europeans, also do very well in the International Math Olympiad and in programming competitions. (But in the one survey of Computer Science grad skills, Americans came out ahead of Russians and Chinese).
Does this mean that they are unusually smart? Much smarter than, say, PISA scores would suggest?
Or does this mean that high IQ denizens of developed countries have far better things to occupy their time with?