Other than the obvious answer that they all have $$$. What work ethics do the great directors possess? What qualities other than (having connections) do all they have that allows them to make the big pictures?
The answer is somewhat simple. The DIRECTOR's are able to maintain a cohesive vision that is their own by communicating and effectively keeping their style over a film with hundreds, and even sometimes thousands of people working on it.
There is the studio, the producers, all the department heads - they all work WITH (not FOR) the director. The director has to answer to the producers and studio. They are his BOSSES, not his BITCHES. If you can maintain your directoral vision answering to that bureaucracy, then I think they are the ones you are referring to. They get to make movies because their style makes the studio money, then they loosen the leash a little on their creative vision.
It's called being a TEAM PLAYER. Orsen Welles had vision. They gave him total freedom on his first film. He lost money. He never had it again.
For me great filmmakers do what they want.. you know, this is my style.. deal with it.
I hope by this definition, you are referring to "filmmakers" to refer to the entire team including DP's, director's, producers, actors, writers, editors, sound dept. etc.
Very few directors are their own producers, editors, writers, casting, etc. Even Spielberg does not have total autonomy. They way marketing over simplifies the process to make it palatable to the general public, you would think that a film's director is the sole author of most big Hollywood films. This simply isn't true.
Most of the world's best known "filmmakers" meaning directors are partners with longstanding producers.
Ron Howard has Brian Grazer. Spielberg has Kathleen Kennedy. Quentin Tarantino has Lawrence Bender. Kevin Smith has Scott Mosier. The list goes on and on.
Filmmaking is a collaborative art. See above as to who the director works for and then understand the reality is that on a budget over $30 million, every single decision a director makes has to be approved by the producers and the studio paying for it.