Literally me

Maybe the person you are now is a shitty person. Not everyone is their best self all the time and maybe if they hadn't done whatever it was than they would be a better person. People make mistakes. Yes, they shouldn't focus on the screw ups and people should move on, but regret is a powerful motivator that is necessary for improvement sometimes. Life isn't about living without regrets, it's about being able to learn from them.