I remember one time when I was a young kid and yo-yos were a craze. I tried to learn all the tricks and then there was a competition at the mall. I told my dad I didn't want to participate because I wouldn't be good enough. Then I saw how they started with basic tricks and I could easily do half of them and would have gotten a prize. I missed out and I knew it.
Don't ask me how I remember such an insignificant moment but it pops into my head whenever I hesitate to do something out of fear of losing.
I really understand you man, I myself what best in chemistry in high school but was too shy to contest in the school versus school quiz, apparently I was better than those that volunteered