It doesn't really matter how much people are willing to pay. It matters how much margin the market will allow you to charge. OpenAI may be a bit better than most competitors most of the time (IMO they keep getting leap-frogged by Anthropic et al. though), but if your customers can get 90% of the value for 50% less, they will bail. There is no moat. Margins will be razor thin. That's not a 1B+ company.

I think the difference between 90% and 95% is huge. As a coder, if the LLM is wrong 10% of the time that's pretty bad, I can't really trust it. If it's wrong 5% of the time, still not great but much better - I'd pay much more for that kind of reliability improvement.