What best explains the effect of Scrooge's personality?

The effect of Scrooge's personality is to make life hard for people around him. He underpays his clerk, Bob Cratchit, so that Bob can't afford medical care for his sick son, Tiny Tim, and his family lives in poverty. He won't even give Bob enough coals for the fire to be warm as he works. To Dickens, it is men like Scrooge, mean and miserly, who spread misery and suffering throughout society by their lack of generosity. They value money over people, and so people go hungry and cold. They have forgotten the importance of human relationships. To correct this problem in Scrooge, the various ghosts try to show Scrooge how important family, friends, and other people really are.
As for what made Scrooge the way he is, Scrooge's fiancee, as she breaks off the relationship, explains that he fears too much being without money. Because of his fear of not having enough money, he has made money his goal in life. It has become all-important. The effect of this is that he doesn't love her anymore. She explains this in the following passage:

"Another idol has displaced me; and if it can cheer and comfort you in time to come, as I would have tried to do, I have no just cause to grieve.”
“What idol has displaced you?” he rejoined.
“A golden one.”
“This is the even-handed dealing of the world!” he said. “There is nothing on which it is so hard as poverty; and there is nothing it professes to condemn with such severity as the pursuit of wealth!”
“You fear the world too much,” she answered, gently. “All your other hopes have merged into the hope of being beyond the chance of its sordid reproach. I have seen your nobler aspirations fall off one by one, until the master-passion, Gain, engrosses you. Have I not?”