To work in the movie business requires a lot of skill but also a huge amount of patience and endurance. However, that goes tenfold for directing. As a film director, you are under unfathomable pressure since you are expected to have a singular vision for a production that is worth millions of dollars but you must also rely on hundreds or thousands of workers. Some of these workers work above you. Some of them may work against you.
There are many reasons why a film may fall apart: maybe the script wasn't tight enough or the acting wasn't very good or the story lacked focus. Fundamentally, nobody makes a movie wanting it to fail - you can have the best director and crew and yet, it just doesn't work.
In some cases, it's just down to everything being a bad fit. Productions can sometimes become so troubled that the director has to be literally taken out of the picture. Whether that actually helps remains to be seen, because results have been... varied, let's just say...
And directors don't always take being told what to do - especially when it's "go away" - by studios, which can lead to all-out (and often very public) war between the parties...
James Egan is on YouTube under Comic Kong with new videos every week. He has written 15 books about comics
1000 Facts about Superheroes Vol. 1-3
1000 Facts about Supervillains Vol. 1-3
1000 Facts about Comic Book Characters Vol. 1-3
1000 Facts about Comic Books Vol. 1-3
1000 Facts about Superhero Movies Vol. 1-3
Twitter - @jameswzegan85