Adding manpower to a late software project makes it later.
Development managers often win their management roles primarily from having been stellar coders while displaying a modicum of people skills.
Programming teams can tell management that the product is one week from being functionally complete every week for the months.
A program can produce the desired results and be so poorly designed and/or executed that it cannot realistically be enhanced or maintained.
For too many managers (especially less technical managers, such as CEOs or CFOs) prototypes appear to be “done.”