Advanced CrossFit is for those who’ve been doing the sport for a long time and those who want to tackle and challenge themselves with more difficult exercises which would not be wise for beginners to attempt to do. To do this, and to be able to do this safely, a good coach is needed.
As CrossFit has literally hundreds of different exercises it would be impossible for you ever do them all, however, once you’ve been doing it a while your body may have adapted to training in CrossFit and this is where advanced CrossFit plays a role and where having a good trainer can help you excel and maintain your advanced level.
Irrespective of how good you are as an athlete every person has a peak, meaning they reach a level where sometimes they can for example do 50 press-ups, sometimes when they try to do 50 they may only get to 45, but on a good day they do 50, or 51 when this happens you can say they are close to the peak of their fitness. It’s not true that you can just go on developing, and those who make you feel otherwise can have very harmful effects on your body later in life. A good example of this is to look at some famous bodybuilders who were known for training with very heavyweights, in their younger age it seems their efforts were convincing, but in their later life, they gave interviews sitting down as they were unable to walk without support and this was because their joints were badly worn and damaged due to very heavy weight training. More on this at RedSunYoutube.