No I'm not kidding. What we have here is an incomplete understanding of the difference between wealth transfer and wealth creation. Ignoring the earned insult to finnboy in post #65 look at the example of the imaginary fence. Wealth flows through NYC, but very little is actually created there.
The imaginary fence is a bogus concept, in that there is no city or region in the world that could survive with a fence around it. No place is truly self-sufficient anymore.
As for the concept of wealth creation, a city based around the banking industry creates enormous amounts of wealth. As a simple example, without the institutional knowledge of NY bankers and lawyers seasoned in the IPO field, companies would not be able to raise capital in as efficient a manner.