And it can invent money from the same black hole, but they don't have to balance. The money spent and money taken in are completely independent. That's the joy of running your own currency.

The downside of running your own currency is that it will inflate. So you have to take some out of the system. Which you can do in any number of ways, but the most obvious is taxation: you take money and burn it. Not the physical notes, obviously, but rather the line in an account book somewhere.

We've actually been doing something a lot like that for a long time. The US government hasn't had balanced books in forever, and consumer inflation during most of that time has been low. It may be doing messed up stuff to the asset markets and may be reaching its limits, but MMT prescribes a smooth slowing of the market rather than a crash.

Some economists suggest just doing away with the fig leaf and stop trying to balance the budget, but rather just keep an eye on inflation and set policy (both tax and spend) accordingly. That's considered a fringe movement at the moment, but even mainstream economists will say that it's not as far removed from reality as you'd expect from a comparison to a non-currency-making entity like a person or business.