"This is because some children made fun of you, isn't it?"
"Nonsense! I'm no has-been. They're the has-beens. I am an am-now!"
It is clear that at this stage Scrooge has been in a state of fun - he has abstained from adventuring for some time, and while he still takes care of his business empire, he is bored and listless. It takes the unexpected arrival of family to get him out of this mood, and rekindle his love of adventuring.