A Christmas Carol by Charles Dickens recounts the story of a cantankerous, miserly, and selfish old man named Ebenezer Scrooge who makes a dramatic change in his life after he is visited by ghosts on Christmas Eve. The ghosts show him what his sad and pitiful life once was before it became what it is now. Even worse, the ghost of things to come shows him how awful his life will be if he does not make a change immediately. While it is true that Ebenezer Scrooge does benefit from the dramatic change he makes in his life and he may have made it for selfish reasons, the "new" Scrooge certainly does not act in a selfish way.
On Christmas morning, the morning after the ghosts' visitation, Scrooge walks around like a man who has just been given sight after a lifetime of blindness.
He went to the church, and walked about the streets, and watched the people hurrying to and fro, and patted the children on the head, and questioned beggars, and looked down into the kitchens of homes, and up to the windows, and found that everything could yield him pleasure. He had never dreamed of any walk, that anything, could give him so much happiness.
This is what Scrooge gets for himself, a sense of happiness and joy which he never had before, or at least not for a long time. His fears do make him act, so to that extent his transformation is selfish. He acts to avoid unwanted, unpleasant consequences.
What is not selfish about his dramatic transformation is how he chooses to bless others now. He is not content just to be a spectator of others' happiness; instead he wants to be part of giving the joy and happiness he feels to other people. The narrator of the novel tells us that
...it was always said of him [Ebenezer Scrooge], that he knew how to keep Christmas well, if any man alive possessed the knowledge.
Keeping Christmas "well" means giving more than receiving, thinking of others more than ourselves, and loving our fellow man more than we love ourselves. The spirit of Christmas is giving and sacrificing for others, and that is what Ebenezer did after he made his dramatic change. A good example of this, of course, is what he does for Tiny Tim and his family.
Perhaps the reason for the change was selfish, but the consequences and resultant actions of the change were certainly unselfish.