Mark Linsenmayer gives Groundhog Day a Platonic spin:
[Bill Murray's character] ends up in a zen-like peace in the midst of his constant activity. He’s figured out what battles he can’t win (saving a dying hobo’s life, actually seducing the one he loves), what difference he can make (even though presumably the damage to a boy falling out a tree would from his cursed vantage be eternally temporary), how to really make everyone around him feel great, and most of all, he’s trained himself to behave morally. Even though he figures out early on how to successfully rob a bank and so be flush with cash for the rest of the day (and likewise, I’m sure there would be more violent and equally effective means to achieve this), this doesn’t become part of his long-term routine, because he’s already got enough.
On a different picture of human nature, he could have become a serial rapist, newly subjugating the town every day, but this, whether or not he explored such dark avenues in his many months of captivity, is not what ends up being satisfying. Given enough time to reflect on it, he (as any of us would, according to Plato’s picture) seeks the good, and given enough acquired knowledge of himself, of social graces, of material circumstances, he’s able to achieve the good unerringly.
So this tale a counter to the “ring of Gyges” example brought up by Glaucon in The Republic. In that case, Glaucon says that man is fundamentally unjust, because if he had a ring of invisibility and could do injustice without consequence, he surely would. Groundhog Day is a demonstration that on the contrary, though someone with such power would try injustice, given the time to really sort himself out, he would turn to justice after all.