They can't just print more money. They have to print based on the value of gold, based on how much gold the USA has, and based on inflation. The more money they blindly print, the less that very money is worth, and if they do that enough, that 100 dollar bill that's in your pocket will be worth zero, even though it says it's worth 100 dollars. And, that's just as good as their having never printed the money to begin with. So, they only print so much each year. And, it costs about 1.5 cents to print one penny. So, they are losing money printing money.