Although there are several possible themes in this play, one such statement might be Greed can turn a virtuous person into an amoral one, eventually eating away their humanity. The character that most obviously represents this is Regina. Although she appears to be a caring mother at the beginning, by the end of the play she is wheeling and dealing in her own husband's murder, simply for more money. She does achieve her goal, inheriting millions and escaping the South to the swinging social life of Chicago and Paris, but she goes alone, having lost her relationship with her daughter through the death of her husband. Greed drives all the Hubbards to move beyond the very comfortable financial stability they have already secured from their business, and each of them sacrifices their morals and values to gain that wealth.
As for the other siblings, Ben is the master of greed, and has been swindling others for years. Regina reminds him, "You couldn't find twelve men in this state you haven't cheated and hate you for it." Ben treats the lives of others as a game, willingly destroying those he feels are below him. Oscar is the least successful at this kind of cold-heartedness, and the others let him know that. Yet he is no innocent. He encourages his son steal the bonds, and then lets Leo take the blame. Oscar enjoys hunting, and gleefully throws his catch away, despite the poor black residents of the town who are starving. Indeed, he even refuses to allow them to hunt in the area.
The play becomes a warning that greed will flourish, and that those performing these deeds will not be punished. She exposes the predatory capitalism that dominated her time, and that she considered a threat to the American ethic.