If they keep missing the hype will burn out eventually

>Why can't OpenAI keep projecting/promising massive data centre growth year after year, fail to deliver, and keep making Number Go Up?

Because eventually, Nvidia will run out of money, so the incestuous loop between Nvidia funding AI entities, who then use those funds to buy Nvidia chips, artificially propping up Nvidia's stock price, will eventually end and poof.

Competing forces are the market's insatiable need for growth every quarter, and other countries also chasing AIs and will not slow down if other countries, like the US, do slow down.