How Developers Stop Learning: Rise of the Expert Beginner (2013)
If you work in an average company who hires average people and you are well above average you quickly risk becoming exactly that. You can be the top 5% (I know it's subjective and controversial yet I'm sure we all have a clue what that means) of developers and this will make it likely for you to be that "local maximum" as everyone will see you internally as a guru.But at companies who are employing the top 5% of the top 5% you will probably won't even make the first round of phone screens.Get out of your comfort zone, and simply learn something new. Go wide, go deep or go both just realize that the moment you feel you are an expert on something it just means you are probably just ready to start learning it for real.tl;dr 
Knowing more than your peers doesn't make you an expert. You are at a local maximum and you need to look at the big picture to avoid being stuck there forever