It’s simple; a lot of the QE from US left US and went to emerging markets, when there was an interest rate difference between those markets and US’s 0 percent. Overtime, the profits earned from those overseas investments stayed overseas. However, when China’s stock market collapsed in 2015 and more money started flowing back into US, US raise interest rate in late 2015. This prompted more return of money back into US, which prompted more economic slowdowns in emerging markets (enhanced by political instability in turkey, Russia, and rising debt in China). With fed raising rates higher and higher, and emerging markets slowing down even more, more and more of the QE money flew back to US. Thus the real estate boom in Silicon Valley, NY, and Los Angeles. Ironically, a lot of China’s QE resulted in the same flow; lots of money went into US real estate. And now we have dollar strength, rising interest rates, emerging market crisis, US gdp growth at 4% in q2