"Extremistan" and "Mediocristan" are concepts from The Black Swan, the second book from Taleb's Incerto.

Mediocristan is the world of central tendency. In non-statistical language, that means most things cluster toward some sort of average—the average is in the middle, and most things aren't too far from it: human height/weights, the number of fans in a stadium, and the daily outdoor temperature.

Extremistan is the opposite: 100 or even 1000 data points, but adding one outlier doubles the mean. Examples: wealth, social media. I heard the average facebook user has about 150 friends; as of today, @realDonaldTrump has 54 million facebook followers.

It can be easy to see Silicon Valley as "judgy" compared to the Midwest, and treat that as a negative; that was my attitude, when I arrived.

But I thought about it and realized the value of good judgment—more charitably, being discerning—is way higher in Extremistan than Mediocristan. In Mediocristan, you can stumble through life, pulling balls more or less randomly out of the urn—jobs, careers, work—and end up pretty much the same. In Exremistan, telling the good balls apart from the bad ones is the stuff of 10x or 100x differences in outcome.

Living in Extremistan is more stressful because decisions are more consequential. You don't get rich in Mediocristan, but life somehow feels easier—more tractable. You do X and the result is Y.