I totally agree with this................. I happened to have learnt how to play the keyboard myself and I got so good at that time that I thought I was 'invincible'. Fast-forward to about 6years later as I practically didn't upgrade myself, I became stuck as I couldn't do the things expected of an average player in the least.
It took greater determination and HARDWORK to start the process again; almost from the scratch.
You're never too old to learn and stopping the process of learning under the guise of 'what is there to learn'? Will only be to our disadvantage in the long run