In competition it is obvious that some riders are much better than others but also a big part of it is who can maintain their cool under pressure. I can see some practical purposes for a contest. It gives new riders and fresh talent a chance to get recognized, and also such a gathering can keep riding alive and growing. But there are also magazines, videos, and jams to serve those same purposes. For myself, entering contests has always been a pointless, stressful mind game.
Most exceptional riders have very high expectations of themselves.
This gives them that extra drive to progress. I have my own standard of riding and level of acceptable achievement which I try to live up to. Greatness can be defined in many ways besides just how hard a rider's tricks are. It's also good to do so some opposite tricks even if they are basic because this forces your body parts to adapt to awkward movements and increases trick linking possibility. Spinning, rolling, scuffing, whipping, turbining, flipping, bike and body varials, etc. are all important and useful.