Printing money isn’t usually a good idea as it generally causes inflation/devaluation of the currency. So while the US could do it, the outcome would probably be devastating.

In basic terms, the more of something you have the less valuable it becomes. This works for things like trading cards/collectibles, but also applies to money.

A good real world example of this recently was the pandemic. Between reduced spending (due to be cooped up) and stimulus money (ppp loans, checks, etc.), a lot of Americans came out of the pandemic looking to spend. This huge surge in spending meant a lot of people fighting over a set amount of goods (since during the pandemic manufacturing took a hit). So high demand and low/constrained supply leads to rising prices. So while people have more money, that doesn’t necessarily mean they can buy more things.