- Your app/solution is solving very specific pains for the user, and
- Will the user see/understand the benefits of solving that pain
It is all about risk. Will your customer (not user, but a buyer) pay for what you're offering and can they clearly articulate the value proposition? I'm not talking about intangible things like: oh, it allows us to communicate more effectively. No, I want to hear things like: we have lost at least $1m because of the lack of direct communication links between our franchisee locations, and this happens every year. We would be happy to pay $150 a month for your solution, or more. Getting to this answer, based on the right questions is likely the hardest job in software planning.
My point is this... Determine how much your customers will RISK paying for, in lieu of just running with assumptions that you're app is solving a great problem. Does this make sense? Let me rephrase this... If you've only tested your product theory or MVP and not your business model, you're going to get seriously stuck! Think: will people buy this?