Filmmaker can be a pretty broad term - are you talking about Writer, Director, DP, Sound Recordist, Sound Designer, Production Designer, etc. etc.
I think each department and position can have a very different way of 'making it' or at least getting to the point where you may be on your way to 'making it' - ie, if you wanted to DP, you would probably camera assist for a while, if you wanted to write, you'd hone your writing skills and then submit to studios, if you wanted to be a Sound Recordist, you'd probably Boom Swing etc. etc. etc.
For a Director, there's no clear path and as much as everyone else you kinda have to find your own way, often funding or finding funding for your own shorts to 'prove' what you can do. I think if you want to be a Director, film school can be a great way to go as it gives you an opportunity to learn film, and make your own films with good crew, good people around you, a good network and good equipment and in a sense learn how to direct, learn what you should and shouldn't do - and in a way prepare you for other gigs you may get.
But then, I'm a Cinematographer and Camera Assistant so maybe some of the Directors can chime in
EDIT:
Also, many have different views of success and what they classify as 'making it'. Some see 'making it' as being a top Hollywood Director, others see it as Focus Pulling on high profile shows, others see it as travelling around with a wildlife doco crew through the jungles of Borneo, Africa, etc.
The path, and the qualities needed I would argue differs depending on your idea of success or 'making it'.