I'm very skeptical about the possibility of building an application using LLMs that meaningfully adds to the utility of the base model and isn't piss easy to copy. If your product is just a system prompt you are adding very little value.
customer-service, code-assist, call-center are a few areas which show early promise wherein customers are willing to pay for the added value. outside of these areas, i am yet to see breakthrough applications for which people are willing to pay. let me know if this is mistaken.