Sounds like this is how he keeps his interest in coding alive and his ability to enjoy it in spite of getting paid to do it. If you only do what you get paid to

Sounds like this is how he keeps his interest in coding alive and his ability to enjoy it in spite of getting paid to do it. If you only do what you get paid to do as a coder, you may grow to hate it and this can be career-ending. You could suffer burnout or just decide to quit or get fired and no one wants you anymore. The first rule of sustainable productivity is taking care of the thing doing the producing. If that's a human, that isn't limited to physical wellbeing, especially if they are producing knowledge work.