Only if the billionaires don't spend, invest or hold it in a bank.

Any of the three, it will go back to the market and result in inflation.

You are describing inflation caused by consumption (i.e. high demand driving up prices).

The inflation the OP was describing is the massive inflation caused by printing money.

The US bond is effectively an IOU representing US dollars the USA owes the bond holder.

For the USA to buy back those bonds they only have two choices:

1. Run an strong economy earning lots of US dollars (i.e. a trade surplus) and use that USD income to buy back those bonds.

2. Turn on the printing press and print lots of USD to buy back the bonds.

That later option would render the USD worthless and since most commodities are priced in USD that would also lead to hyper inflation.

> Pay off those bonds

I don't think that would happen. They will just borrow ever more. Which if debt increases slowly enough, is sustainable but causes inflation.

How do you mean? If the Fed creates new money and buys bonds with it, the Fed can continue to hold them forever (really just until they mature) if it wants to. Then the Fed is more or less part of the government, so when the bond matures the Fed takes the bond to the treasury which gives it cash, then it gives the cash back to the treasury. It's like the bond evaporates into nothing when it matures while the Fed is holding it.

If the Fed theoretically bought all the bonds then it could obviously no longer increase the money supply by buying bonds, but we're a long way from that, and even then the Fed could still create new money and give it directly to the treasury to spend in lieu of collecting taxes. Or in the utopia where buying all outstanding government debt and funding the entire federal budget out of new money still hasn't caused the desired amount of inflation, to use to enact a negative income tax.