Having an idea doesn't mean you're going to succeed. Prototyping that idea and then garnering opinions on it will result in nothing more than that…opinions. Opinions are not worth a thing. They're no evidence of anything because they're subjective and inconsistent. Having a great idea that you can be sure will work, that you know people will pay for even before it's fully developed probably does point to success. But how can you get to that point? How can you be sure the idea will work and be confident that people will pay for it?