There are two important points by Keynes that are relevant:
1. The market can remain irrational longer than you can remain solvent. Even if you're betting on a crash, it will probably happen after you get margin called and lose all your money. You can be absolutely right about where this is headed, but keep your personal investments away from this.
2. The value of a company isn't determined by any sound fundamentals. It's determined by how much you can get a sucker to pay (aka Keynes' castles in the air theory). Until we run out of suckers OpenAI will be able to keep getting cash infusions to pay whoever actually demands cash instead of stock. And as long as there are suckers that are CEOs of big tech companies they are going to be getting really big cash infusions.
[1] https://www.pgpf.org/programs-and-projects/fiscal-policy/mon...