What's the point in missing out on something because of self doubt?
It sounds ridiculous to limit your own potential and happiness just because you're afraid to lose.
Truly if you look at it from a wider perspective, and you gave something your all and put your heart into trying to 'make the team' or 'getting the job' and you don't. You haven't lost anything. You've gained knowledge and experience. That is way more important than a title or a spot in a team.
There's always more jobs and always more opportunities in life, the most important thing is that you start and you learn from the journey.