Trillions? Even if you were referring to the amount of money made by all American investment banks in the last several years, you'd still be off by a few orders of magnitude.
Research the Federal Open Market Committee or GSE's.
The banks made it coming and going. And still are. I also wanna point out banking isn't the only sector enjoying these golden times. The drug war, terror war, general war, oil, food - all enjoy generous subsides/funding from our government.