Nobody's perfect. We all make mistakes, and part of being any kind of creator is being able to stand up and admit that something you made wasn't quite as good as you hoped it would be when you started out. Even the most successful people in any line of work are capable of doing things wrong from time to time, and this is especially true in the world of Hollywood.
Actors, screenwriters, directors, and plenty more people involved in the movie-making business will readily admit that some of their projects would have been better off never being made. Directors tend to be quite proud people, but none of them have a truly flawless body of work to look back on. Some will openly admit that they made a dud, while others blame executive interference and circumstances for their less popular productions.
Some directors even go as far as getting their names removed from the credits in order to disassociate themselves from their bad films as much as possible. A few of these films aren't even bad and were warmly received by audiences around the world, but the directors definitely wouldn't mind going back in time and never making them in the first place.