Of course, a mass amount of people work towards a successful film effort, but the brand 'Tom Cruise' will fill the seats.
writers, casting directors and advertisers
Sometimes, those categories mentioned above do thankless jobs, and they deserve much more credit.
However, they're not marketable, and for the majority of people, they're not going to see a film because of the 'casting director'; they're seeing the star of the picture.
I don't really approach films in way, but so many people do.
It's why Nicholson, Hanks, Cruise, Dicaprio, Crowe, Depp, Damon, etc. . . are paid 10-20 million per picture. They're a valuable commodity.
Currently, the industry is lowering its payments, even for pricey A-listers, but the 'bread and butter' often comes from the star.
How many people will dismiss the concept of a movie, but elect to see it because Christian Bale[or any other popular actor with a fanbase] is in it?