If that is the bet they are placing, it is a bet they will lose. The power and capabilities of US corporations does not rest solely on those corporations, and as the wealth, influence and power of the USA undergoes "a massive contraction", they will find themselves similarly degraded. They might be the big fish in the big pond, but only because everyone knows there's a bigger fish (the US government). Once other countries, and other corporations, no longer care much what the US government thinks, US corporations will find themselves in a very, very different situation.
Of course! I think at some level the people at the top know that this American capitalism is not competitive. The last 5 years or so have been basically the whole country realizing that our system is not competitive. And, the last 1-2 years have been collectively, the world re-calibrating on this fact.
The monopolists don't care though. The power is too intoxicating.
I mean, listen to discussions here. "What's your moat?" -- that's how American capitalists think. Not "What value does your company provide to the customer", but what extra force, beyond simple-minded fair market competition, are you leveraging, to ensnare the customer. The game is to ensure that customers cannot choose another business over yours on its merits. That works in the short term but it's extractive. Eventually, the parasite must stop sucking blood for the host to survive.