2009 QE? Necessary because of 2008 bank de facto nationalization. That was necessary because of intervention in rates which caused overleverage but also bank profits dependent on carry trade. That was thought to be necessary to fight the dot-com bust and 9/11. The dot-com boom was exacerbated by low rates to fight the Asian crisis, carry trade from Japan's bust-fighting measures, LTCM spillover, moral hazard causing abnormally low rates for GSE's, etc.
Can trace a lot back to Congress in the 70's through 90's. Also 1987 response to crash (market meddling and low rates including distortions in long term rates). Before that wage and price controls and leaving the gold standard. Only one simple change is needed: dont meddle in the markets, especially not in the credit markets.
When we became a debtor nation, we sewed the seeds of China being in a position to hold power over us. We became dependent on other nations to finance our debt and continued spending. And if they stop purchasing our treasuries, bonds... we’re in trouble. That’s my take on it.