This is why compounds change hands so many times before they are successfully commercialized. Running a phase three study costs much more than a phase two. Pharmaceutical companies partner to pool the risk and share the cost.
This is 100% true if you did not do your due diligence before you all committed to whatever you are building. One of the best ideas is to hire someone like me who has failed at building something and helped other people try and iron out some of the unanswered questions. Someone else already mentioned this. He is likely just as capable. It may take a fresh set of eyes and a fresh outside voice. I can point you to other people as well.
The actual potential market size may not matter. It is never a great idea to build a business from the top down. Instead, build from the bottom up by seeing if you can sell your product to whoever you think is the customer. The true test is right there. If you cannot get all of the stakeholders to the table due to needed partnerships, it provides another precautionary red flag.