It's very clearly stated in the film: You make your own choices, and what you're always fighting is ego.
“If you're doing something new you've got to have a vision. You've got to have a perspective. You've got to have some north star you're aiming for, and you just believe somehow you'll get there, which kind of gets to the passion point.”
“In Hollywood, what they last saw you in is what you are. It's hard to break away from that.”