Well, to paraphrase Adam Smith, it's because there is something in us that dearly loves to be a sub:
"It is the misfortunes of Kings only which afford the proper subjects for tragedy. They resemble, in this respect, the misfortunes of lovers. Those two situations are the chief which interest us upon the theatre; because, in spite of all that reason and experience can tell us to the contrary, the prejudices of the imagination attach to these two states a happiness superior to any other. To disturb, or to put an end to such perfect enjoyment, seems to be the most atrocious of all injuries. The traitor who conspires against the life of his monarch, is thought a greater monster than any other murderer. All the innocent blood that was shed in the civil wars, provoked less indignation than the death of Charles I.
"A stranger to human nature, who saw the indifference of men about the misery of their inferiors, and the regret and indignation which they feel for the misfortunes and sufferings of those above them, would be apt to imagine, that pain must be more agonizing, and the convulsions of death more terrible to persons of higher rank, than to those of meaner stations."
Brad DeLong