They also get sales, which prop up the extraordinary share price. That seems to be the main point of the circular deals.

Nvidia is basically the house loaning money to the gamblers. They don’t care if the gamblers win or lose. They just care that people keep playing.

Even if topline is being artificially inflated for marketing reasons, if there's a pile of offsetting contracts, I would imagine there's always a risk of a differential in conditions that causes them to resolve asymmetrically. If company A and company B both have 100T$ of contracts with each other and 1T market cap each, it's hard to actually make them inert, any slight miscalc and one company goes bankrupt and its assets go to the winner.

Hard to imagine a perfectly identical offsetting transaction let alone triangular or circular.

Nvidia and constructions companies certainly are. And a lot of middle men...