Ebenezer Scrooge was a banker.
The reason Ebenezer Scrooge was so rich was that he made his living lending other people money and charging interest. He worked in a counting house, and he owned the counting house because it was just him and Bob Cratchit. A counting house was a business for exchanging money.
The door of Scrooge's counting-house was open that he might keep his eye upon his clerk, who in a dismal little cell beyond, a sort of tank, was copying letters. (Stave 1)
Being a money-lender is not a very pleasant profession, because people often do not want to or are unable to pay back the money they have borrowed. This might be one of the reasons why Scrooge became such a bitter man. He saw the worst of human nature, and became resentful.
One of the reasons that Scrooge was not willing to give away money to the poor is that he seemed to be exploiting them in his business. When Scrooge is visiting in the future and asks to see emotion at a death, he unwittingly produces an image of people celebrating his dying.
“To whom will our debt be transferred?”
“I don't know. But before that time we shall be ready with the money; and even though we were not, it would be bad fortune indeed to find so merciless a creditor in his successor. We may sleep to-night with light hearts, Caroline!” (Stave 4)
The man and woman discuss how Scrooge would never relent and give them an extension on their loan when they were unable to pay. He had a reputation for being hard-hearted and uncaring with his clients. This image shows how Scrooge affected everyday people’s lives in a negative way.
Belle accuses Scrooge of having a “golden” idol, caring more about money than people. It seems that in building his business, Scrooge became obsessed with money and wealth at the expense of his relationships. This is why when we see Scrooge at the beginning of the book, he is almost all alone. He even rebuffs his nephew’s attempts at friendship because he has no money.