You never know 'enough'. You just have broad interests and see how all things are more interlinked than any one specific branch of knowledge captures. So you naturally wander through a host of subjects rather than exclusively deepdive into a single specialization.

This. Often you'll also put something down for a while only to pick it up again years later, dusting off your old know-how.

Learning is a never-ending process in which progress is not stable and regression also happens. In that sense it is sisyphean.