How do the past events in Scrooge's life influence his personality in Stave 1?

The Scrooge is Stave I is a bitter, reclusive person who is disillusioned with humanity and has turned all his attention to making and hoarding money. We learn, as we travel with Scrooge and the Ghost of Christmas Past into Scrooge's former life, that the choices Scrooge once made formed the person he has become.
We realize as we watch Scrooge's response to Fezziwig's long ago Christmas dance that Scrooge was not born a miserable person. At one time, he enjoyed a good party. To this day, he looks fondly on the sociable, generous Fezziwig. We also learn that Scrooge was once in love and about to marry.
Scrooge threw all that away by becoming obsessed with making money. We realize, as we witness his long-ago breakup with his fiancee, that he has taken a basic truth—that all people have material needs and are respected for being wealthy—to an extreme. He has started to use people and love things, not vice versa. He has put getting rich ahead of simple virtues like love, generosity, and kindness. As he gradually isolates himself, he becomes more and more bitter and withdrawn until, by the time the story opens, he has forgotten what it is like to live a normal life with other people.
Now, however, seeing the past, Scrooge's long-frozen emotions begin to soften and thaw, and he begins to have regrets over the decisions he made as he is reminded of how much happier he once was. He realizes he might like to be more like the generous Fezziwg and to have some of the love he threw away back in his life.