Is it true that newly printed money is “loaned” into existence?

So after some research my understanding of the system in the USA is:

– fed reserve prints money

– fed reserve buys bonds/t-bills (aka lending money to govt.)

– this money goes into circulation in the US economy

– the debt is just added to the govts balance sheet and never fully repaid

How has this been sustainable? If nothing tangible produced that currency how can a country survive like that? New dollars are competing with old ones but the new ones have nothing of “value” that produced them (time at work, goods produced etc).

What am I missing?