When you deposit a cash into a bank you are no longer a legal owner of that money but the banks are. They keep 10% of your deposit on reserve and can loan out 90% of that money to someone else that other person can deposit that money into another bank and then that bank can loan out 90% and so on. This is known as fractional reserve lending. Specifically, in USA, things did not just stop there. When central bank announced zero percent reserve requirement for all depository institutions, banks can now create infinite amount with no reserve for them to use in gambling.

When banks hold your deposit, they can along with hedge fund gamble with it through investment in financial instrument such as derivatives and securities. They do this in order to make superior returns and most of the time. These instruments are basically just bets on if the price of an assets will rise or fall but when taken to the extreme it can get ridiculous. Like how Enron Corporation ended up bankrupt by using financial instrument to bet on the weather. These crazy classes is what brought down the housing market and the subsequent global economy in 2008.

However, the problem today is that banks are playing with so many derivatives and sometimes stacked on top of each other with leverage multiplying factors that nobody actually knows how much money is tied up in this gambling. Some estimates put the derivatives market at over one quadrillion dollar which is over 10 times the global economy.

Imagine what will happen to your money if the derivatives market with one quadrillion dollar collapsed? Think about it when you have time.