That's not quite the same thing at all as your credit card's revenue stream as you have a ~18%+ monthly interest rate on that revenue stream. If you recall AMZN (& all startups really) have this mode early in their business where they're over-spending on R&D to grow more quickly than their free cash flow otherwise allows to stay ahead of competition and dominate the market. Indeed if investors agree and your business is actually strong, this is a strong play because you're leveraging some future value into today's growth.
As to openai, given deepseek and the fact lot of use cases dont even need real time inference its not obvious this story will end well.
How long can they maintain their position at the top without the insane cashflow?
Moore's law seems to be against them too... hardware getting more powerful, small models getting more powerful... Not at all obvious that companies will need to rely on cloud models vs running locally (licencing models from whoever wants that market). Also, a lot of corporate use probably isn't that time critical, and can afford to run slower and cheaper.
Of course the US government could choose to wreck free-market economics by mandating powerful models to be run in "secure" cloud environments, but unless other countries did same that might put US at competitive price disadvantage.