I am not an entrepreneur, but I don’t think it’s that simple.  Entrepreneurship is all about overcoming the odds.  I believe that if all entrepreneurs decided to quit when the data were telling them to, there would be very few successful startups.  As Nicholas Nassim Taleb puts it in his insightful book “The Black Swan”, “some blindness to the odds or an obsession with their own positive Black Swan is necessary for entrepreneurs to function”.

My guess is that entrepreneurs decide to call it quits when they just don’t “feel” it anymore; when deep inside their gut feeling and their undaunted optimism are just not there anymore; when they don’t have the strength to dismiss another round of gloomy data as yet another obstacle to overcome; when they themselves lose faith in the ultimate success of what they are doing.