There are many factors that contribute to your success at work… what unique skills you have, how committed you are, whether you have strong ideas, and (especially) if you’re willing to fail. But if your success at a company depends on someone else’s failure, it’s time to go.
Any company that can only offer you greater opportunity because someone else fell short doesn’t know how to capitalize on employees’ talents and strengths. It’s just filling boxes on an org chart. If someone else need to fail for you to move ahead, take your talent (and your future) somewhere else.