You can rent a H100 GPU for $4/hour. [1]
300k tokens for that hour.
OpenAI charges $6.
Those are pessimistic assumptions.
3.99 at 8x instances, with a minimum 2 week commitment. Good luck getting 70% usage average during that time. Useful when you're running a training round and can properly gauge demand, not so great when you're offering an API.
Can you keep that GPU 100% saturated at least 16 hours per day every day of the week?
If not, you aren't breaking even.