Even some of the smartest people in the world fall victim to this. For example, Elon Musk originally estimated that SpaceX would launch its first flight in November 2003. The first launch, which still failed, didn't take place until March 2006 and the next two launches also failed. The first successful launch didn't take place until September 2008, a delay of almost five years.

In his biography, Elon Musk acknowledges that his original estimates for SpaceX were completely ridiculous and based on his experience with writing software and ignorance of the realities of building spacecraft.