It's essentially related to how the banking system works, and how it's regulated. QE money is asset money, it sits on the left hand side of the bank's balances

It's essentially related to how the banking system works, and how it's regulated. QE money is asset money, it sits on the left hand side of the bank's balances. The money that everybody actually uses is bank deposit - liability money, which sits on the right hand side. Liability money dwarfs asset money in modern economies. The rest is then a question of what happens when you inject asset money into a banking system, and that depends on the regulatory framework. In the modern banking system capital controls have taken over from asset liability money controls, and that is essentially what has stopped the hyperinflation that some people predicted. If you look at the deposit money quantities, well the normal rate of expansion for the US is approximately 2x decade, and that continues to be the case.