The fear of failure is what holds me back from attempting ctb personally. I do feel like if someone has a method plan, and they have done research and they feel confident that the method will succeed then this may give them the courage for ctb.
Of course only the individual knows when it's time to leave, I believe that it's a feeling they have. I think that if I had a guaranteed, peaceful way to exit then I would have no problem in going through with ctb. Ctb really is so difficult, I wish that we lived in a world where our right to die is respected and then we could just exit peacefully without ever having to worry about the chance of the method failing.