It’s likely that every culture throughout human history that has had a written tradition of transferred knowledge has passed down some aphorism about not assuming that some anticipated positive outcome is an inevitability. Even regardless of whether or not you can control the result, it’s best not to operate under the assumption that it can’t not happen.
Now, there probably aren’t many people out there who buy the idea that former Pittsburgh Steelers quarterback Ben Roethlisberger has any chance of failing to be inducted into the Pro Football Hall of Fame. But it is understandable that he wouldn’t take it as such a given, especially after watching some of his former teammates have to wait their turn—and still watching others wait who may never get in.