You might say “What? Already? What a short and/or easy game!”, and you’d be wrong. You see, like Mario 64 and Mario Sunshine before it (in fact, like virtually every Mario game, actually) just beating Bowser at the end is The End as such. You only need 60 stars to do that, “win” the game and see the credits. So with that many, I beat the boss and completed the game.
But that’s only half the stars! Now there’s the task of mopping up the rest of them, mainly from alternate goals in galaxies I’ve already completed, and also some more in galaxies not yet unlocked. I went back and did some more (including collecting 100 purple coins on an ocean level, which took aaaages as I kept killing myself accidently…) and now I have 66 stars.