Failure is always an option. Sometimes, failure is even the best option.
A good project manager plans for all likely contingencies which should include the many routes that leads to a catastrophic conclusion. There are always far more ways that things will go wrong than for things to go right. The path to success is narrow and difficult to follow. The paths to failure is basically everything else.
Many project leads believe in only planning for the best. They do not make plans for the many, many things outside of their control. They rely on hope to get them through. They hope that the bad things won’t happen instead of proactively working to manage those things.
Failure is the best opportunity to learn. When you succeed, you generally know what you did that led to the outcome. When you fail, you learn something new and unexpected.