I find a lot of truth in this. Once you become experienced, competent and skilled at something it is very easy to have reluctance to start something brand new. You have to confront being a complete newbie with all that entails – lots of trying, lots of failing, lots of work to improve your skills, lack of validation compared to efforts in your comfort zone.
It is far, far easier and less stressful to stay in your comfort zone. But that is not where the growth lies.