Karl Groos wonders: why might a child find it annoying or scary when someone drops a heavy pot and makes a loud noise—but fun when doing it themselves? The joy of being the cause. He observes that this authorial joy, as motivation, explains much play behavior of humans and animals.
And likewise Piaget, referencing Groos (via Daro, unknown original source): What motivates children’s progress in their intellectual development? The joy of being the cause.
This is part of why video games are so effective (Games are an aesthetic medium of action, Enacted experiences can create intense personal connection to authored targets).
(compare to Koster, who emphasizes mastery as the source of fun in games)
Groos, K. (1901). The Play of Man. Appleton.
Dan Meyer - Learning the Wrong Lessons from Video Games (2018)
Koster, R. (2013). Theory of Fun for Game Design. O’Reilly Media, Inc.