Posted by Double M
You are probably not the best at whatever you think you are the best at doing. Even if you are, you won't be forever.
In the 1990's Michael Jordan was the best basketball player. That means there are billions of people that were never as good as him, even though there are tons of people that were really, really good.
10 years post-retiremnt? Michael Jordan is not the best basketball player in the world. Prior to the 1990's MJ was really good but wasn't the best player in the NBA.
The point: Even if you are one of the best at what you do, there is probably someone that is better at that specific thing. Further, even if you are the best, chances are you won't be the best forever. At some point either your skills will falter or someone will come along with better skills (or both) and you will no longer be the best.
This means that you'll need to learn how to live life as "not the best". For an ultra-competitive person, this can be really hard and I've seen it cause drama.
For an non-sports example, look no further than honors programs in college. A good honors program only takes kids that are considered the best in high school. Suddenly, all of the "bests" are thrown together and only one of them can actually be the best. Some people, when they move from being the best to being the 3rd best or 10th best or almost last, freak out and end up washing out purely because they can't handle the fact that they aren't the best/smartest/biggest teacher's pet/etc.
All of this can be avoided if you simply understand that there is someone better than you out there and learn to live within that fact.
Disclaimer: This doesn't man you should just give up or that you should quit trying to improve yourself.