They're selling GPUs in exchange for scrip which may or may not be able to pay Nvidia's operating expenses depending on whether AI has a profitable business model. This isn't hard to understand.
Nvidia gets real cash, pays TSMC, etc.
The people in real trouble are companies like CoreWeave, Oracle, etc. that took an IOU from OpenAI (for example) to start a buildout, entirely debt financed. It works out so long as demand keeps going up, but the moment the music stops and that debt comes due and there's no revenue to pay it, game over.
Nvidia's concern isn't not actually getting paid, it's being faced with a glut of cheap, depreciated GPUs flooding the market impacting their future revenue. They'll live.
But OpenAI, not being able to pay CoreWeave, for example, that IOU, and then private credit coming for the debt payments from CoreWeave, is what would start the chain reaction. We may actually get to live to see Oracle fall.