Don't be fooled. Having a prototype raises as many questions as it answers if not more. Business people pretty much expect you to be able to build something, none of this is really rocket science. What happens after you build a prototype is that your prospective investors check off a little box and then begin asking other questions around sales, production, expansion, costs of development. The focus becomes - why haven't you sold it? If it's so great, why don't you have pre-orders? Is your model really scalable?
Business people are not enamored with the product or all the little nuances you think make it a block buster. Trust me - I created this video game that made inner-city kids LOVE algebra. If you had ever taught in the classroom, you would have thought you had seen a miracle when I showed you a room full of kids who were normally discipline problems caring less about math, being distractions in the classroom, and having given up on education, sitting there collaborating and playing with excitement a game that was teaching them algebra. It was phenomenal.
Yet my presentation of the prototype was the first 5 minutes of a meeting. Nobody asked cool interesting questions about the game, the development, the insights. Instead, the other 55 minutes and every ensuing meeting for months afterwards was all about business. How are you going to sell it? Who are the customers, what are the costs? What are the price points? What's the sales cycle?
A demo only opens the door... to a waiting room.