The article is mistaken about one thing: the size of the financial sector is not limited by the total wealth of the world. Eg: there could be derivative contrac

The article is mistaken about one thing: the size of the financial sector is not limited by the total wealth of the world. Eg: there could be derivative contracts (insurance or derived bets) for cumulative values much more than the value of the underlying asset (arbitrarily high, in principle). This is a big factor in what makes the global financial system so fragile. If the finance industry keeps skimming a fraction of all the money flowing through it then financial hubs like New York city and London could keep becoming more expensive.