#1 If you go $200,000 into debt on credit cards you will have to pay it back plus interest. You pay to "rent" this money. Same with the USA if we buy so much more from China and they hold US Treasuries rather than spend it, which in fact is what they do. Once more interest is collected as it is from all debtors.
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We expect the people buying bonds to put the interest into buying more bonds instead of collecting the money. Eventually, with the accumulation of bonds the potential interest will build until there is no way to createn enought more bonds to satisfy it, and no way to pay the interest without bankrupting the nation. We are deferring a disaster through employing methods that make the eventual disaster worse.
One way they collect is to buy productive assets in the USA.
AKA colonization. Buy property that yields rents and factories that produce automobiles. That's what Toyotoa does. Stupid Americans hail the job creation by Toyota while the profits go to the Japanese. Was in Forbes that Toyota is 95% Japanese owned.