Elon Musk has achieved what others might have conceived as impossible. He takes enormous risks and never seems to fail. Why? Simply because he doesn't believe in failure.
Co-founder of SpaceX, Jim Cantrell, told Farnam Street that Musk succeeds because he believes he, his ideas and the products they produce will succeed.
There is a very "if you build it they will come" vibe to this ideology, but it's one more entrepreneurs should take on. Believe in what you are producing -- truly and fully believe in it. Don't think that it can fail. Find a way to make it successful, and it will be.