Attended the Chicago Lean Startup Challenge this summer. They push teams to do experiments to determine if their guess/business idea is solving a real need of a customer segment. This 8 week program has saved a lot of companies from building the wrong product and addressing the wrong problem. Watch some of the videos on BuiltinChicago.org to hear how the interview process lead to a major pivot and the start of a company. Summary: Don't built it unless you have done considerable customer interviews and determined A. you are addressing a morphine problem not an aspirin problem and B. The customer base will pay for your solution. Then you build and A/B test. :)