In that time the world has mined perhaps 30,000 tons of gold, or about 950 million ounces, worth at September 2015 prices a little more than a $Trillion. It is easy to create debt – central banks "print" currencies
by borrowing those currencies into existence. Debt increases, currency in circulation increases, and until it crashes, life is good for the financial and political elite. But debt increasing 60 times more rapidly than gold indicates that debt is growing too rapidly and due for a reset.

It is a tangled web of debt, counter-party risk, obligations, and unintended consequences. From an interview with David Stockman:

Stockman goes on to paint a grim picture and says, "What happens when the financial breakdown comes is there is a great margin call. Everybody says 'I want my money back and I'll take your collateral if I don't get it back. If I do take your collateral, I will sell it for whatever price I can get and cut my losses.' So, this is truly a house of cards. The whole pyramid of debt and what we call hypothecation and rehypothecation of financial assets, that is the real bubble. That's what people don't focus on enough. Sure, you can think of stocks that are a bubble, like Tesla [Motors] and its current price of around $250, or the biotech index which is trading at hundreds of times earnings is crazy.