He learned his stingy ways and attitudes were wrong and unfair and made him completely miserable. He sends a turkey to Bob's house, gives Bob a raise, and lets Bob have the day after Christmas off from work. He attends his nephew's Christmas celebration. He even gives money to the poor and homeless. Dickens teaches his readers the importance of joy and cheer in life.
Happiness is imperative to make life bearable.
He realizes that he has the power to make others happy or miserable. Every reader can see that Scrooge's way is unhealthy and depressing. With the help of his deceased friend, Jacob Marley, Scrooge manages to transform his life before it becomes too late. The reader can predict that in the future Scrooge will have many more joyous Christmases.