You hit the nail on the head: This whole essay is based on a false premise (which nonetheless is strongly believed by PG). Cambridge only seems to be a "smart" town if your social group consists of people associated with MIT, and you're only likely to end up in that social group if you were part of the middle class when you moved there.
If you are merely rich, your money can be easily taken from you by more powerful person in Moscow.
And if you didn't know, Russian is a second class citizen in Russia.
All in all, one message per city is insufficient. It all depends on the people around you.