Lots of people spent their whole money to create a film because they think that they will earn more than they spend. For example, few months ago, a Turkish director spent all of his money to create the movie "Fetih". I think he earnt that money and much more of it.
Lots of famous directors like Steven Spielberg, Alfred Hitchcock, Woody Allen made amazing movies. They will be remembered in the future with their movies. Its an important type of art. They try to create a special and different movies for people because nowadays, lots of stinky movies are released and their subject are almost similar. Creating a new movie is like creating something new which you can choose everything about it.
As a result, I wanted to say that making a movie is very difficult and it needs sacrifice. Everybody talks about movies and actors but directors stayed in background. Few people can remember their names but they do most of the jobs.