Customers don't know what they want. There's plenty of good psychology research that shows that people are not able to accurately predict how they would behave in the future. So asking them, 'Would you buy my product if it had these three features?' or 'How would you react if we changed our product this way?' is a waste of time. They don't know.
Eric RiesThe biggest start-up successes - from Henry Ford to Bill Gates to Mark Zuckerberg - were pioneered by people from solidly middle-class backgrounds. These founders were not wealthy when they began. They were hungry for success, but knew they had a solid support system to fall back on if they failed.
Eric RiesWhen Steve Jobs and Steve Wozniak created Apple computer in a garage in Palo Alto, it heralded the beginning of the PC revolution that ultimately dealt a death-blow to dozens of older companies.
Eric Ries