Passion x Bias

“Confirmation bias is a tendency for people to favor information that confirms their beliefs or hypotheses. To put it simply, we like to be right. We tend to agree with ideas that align with other ideas we hold as true.
People exhibit this bias by gathering or remembering information selectively, or by interpreting information in a biased way, to confirm or support what we already believe. This contributes to overconfidence in our experiences and personal beliefs.” - Build It Like A Startup, Greg Gehrich

“The seeds of opinion can be dangerous things. Once we begin to be persuaded of something, we not only seek out confirmation for that thing, but we also refute fact even in the face of incontrovertible evidence.” - The Information Diet, Clay Johnson 

"An intelligent opinion is still a guess. The dumbest person with a fact trumps anyone with an opinion." - Steve Blank 

"There is no such a thing as a negative feedback." - The Truth about Feedback, Alline Watkins

"Hurt me with your worst truth, don't delude me with your best lie."

Seek for contrary data. List your negative assumptions. Try to understand WHY someone that is your potential customers will NOT USE your product. This will help to avoid many drop outs. 

"How can we eliminate this pervasive and insidious tendency? It’s simple: try to prove yourself wrong, not right. Substitute leading questions that support your ideas for ones that support the opposite." - Build It Like A Startup, Greg Gehrich

"Truthiness is a quality characterizing a "truth" that a person claims to know intuitively "from the gut" or because it "feels right" without regard to evidence, logic, intellectual examination, or facts." (From Wikipedia)

"Blindly following the maxim that good managers should keep close to their customers can sometimes be a fatal mistake." - The Innovator's Dilemma

"If a Startup is search, so probably your first idea is wrong." - Steve Blank