What will be the impact of said creditors calling for repayment? Who are the top creditors percentage wise?
It is not a question of creditor ruining their own investments.
If the federal government was running a surplus, this would be going away on its own, but the federal government is running enormous deficits and financing that new debt is what is going to cause the collapse.
Look at it this way, if you purchase a house and finance it, the bank looks at your income (analogous to tax revenues of the federal government) and the amount you wish to finance (the federal debt) and makes a determination as to whether you are good for the money.
Finance a second house (the next year's federal deficit) and the lenders make the same calculations, but now the borrower already has some debt so the loan is a little riskier.
By the time you have financed your 5th (or 20th) house, the lenders are going to worry that they will not get their money back, so they cover that risk by setting their interest rates higher and higher. Given that the treasury refinances already-existing debt over time any increase in market interest rates means you pay more for the money you are borrowing
today, but eventually, you will pay more for the money you borrowed
decades ago. And the United States have been deficit spending since around 1833.
While a bank can foreclose on homeowner in default and at least get the property back, the purchaser of a T-bill is simply relying on the federal government to pay back the debt. The T-bill holder gets no collateral, so that loan is riskier, especially as the amount financed gets larger and larger.
Like the San Andreas fault and the Yellowstone caldera, it probably won't come today, and probably not tomorrow, but eventually and unavoidably and when it does,
it will be catastrophic for millions. We cannot control when the San Andreas fault or the Yellowstone caldera, but we can avoid
this collapse, but it would involve taxing a lot more and spending a lot less. The federal deficit was $1.4 trillion in FY 2022, so we need to spend $700 billion less and tax $700 billion more (or some combination thereof), just to break even, to stop making things worse. Does anyone sense an appetite for such cuts and tax increases on that scale?