What causes the downfall of the White family, and how is it related to the theme of "The monkey's paw"?

I think that greed and wish fulfillment caused the downfall of the White family. At the beginning of the story, the White's seem contented in their cozy house. The arrival of Sergeant Major Morris and the paw provokes their inner greed and they are drawn to interfere with their fate. The wish motif is often tied to greed and the White's are no exception. Their first wish, for 200 pounds, causes them misery and their subsequent wishes try to counteract their initial wish. Things just get worse for the white's after that.