There is always a bigger fish. That is a lesson you need to learn early in life. You strive to be the best, but there is always someone better.
This is a hard lesson for some people and one that Brazilian Jiu Jitsu illustrates perfectly. Years of training go into perfecting the art. The belt progression is much slower than other martial arts because there is a lot to learn. So it is not uncommon to have trained for a couple of years and still be a white belt. This obviously means there is a large arc of skill levels in any one belt level.
You are going to lose, and lose often, especially when you begin. You can’t let it discourage you though. One of the great appeals of Jiu Jitsu is when you begin to see all the pieces come together. You may take months learning a collection of maneuvers and then one day see how they all come together. Then you will see how other maneuvers tie into those, giving you a menu of different options to try.
You will get better. You will end up being a winner. But even when you do, you know you must continue to refine your skills. Because there still is someone better.