Understand you 100% - thats why I force myself to study maths as a "hobby" at a remote university. Its completly useless these days since I will probably never reach a level where I am better than current frontier models - but it sharpens my own mind, just by doing it. I would compare this to the same principle which applies to physical training - its not essentially required these days anymore to be physical active, still its quite helpfull. It would be dumb to not use it - since it is usefull, but its also dumb to see yourself getting dumber and not doing something against it.