In this story, Prince Prospero seems to symbolize those people with wealth, status, or some kind of authority, who believe themselves to be somehow above or outside of those problems, such as the ability to die, that affect everyone else.  Despite the fact that there had never been such a deadly disease, a disease which had ravaged and taken half his kingdom, the prince still seems to think that he can somehow escape it.  The description of him as "happy, dauntless, and sagacious" is ironic when one considers that his happiness comes at steep a price (his integrity); further, one who runs away from one's kingdom and people can hardly be considered brave, and neither is he wise who believes that he can escape mortality.  

Prospero is rich enough to possess a castle far away to which he can retire and invite one thousand of his most carefree and healthy friends to attend him.  He can stock the abbey with all types of provisions, even welding the iron gates shut so that no one can get in or out.  However, his wealth and status cannot protect him from death; they do not entitle him to safety when everyone else is prone to disease and decay.  And in the end, he is not immune to death.