Pride goes before destruction, and a haughty spirit before a fall (Prov 16:18)
Prince Prospero is extremely proud, feeling that he is above all others. He summons his court and takes them to his abbey, an "extensive and magnificent structure" which is his creation. Having fortified this abbey physically and stocked it with provisions, "the courtiers might bid defiance to contagion" of the Red Death.
With his "fine eye for colors and effects," he has the rooms decorated boldly in different colors so that they glow "with barbaric luster," and reflect his haughtiness. Poe's narrator comments that because of the boldness of his designs, some "thought him mad"; however,
It was necessary to hear and see and touch him to be sure that he was not.
While those outside the fortress succumb to the plague, the courtiers and Prince Prospero engage in revelrie. In his pride, the prince fears no threat to his or his courtiers' lives. But, the failure in his haughty mind to allow the possibility of the Red Death finding its way into this fortress is the prince's nemesis. Even when confronted by the sinister interloper, the haughty Prospero draws a dagger against the Red Death, convinced that he can kill this intruder.
There was a sharp cry--and the dagger dropped gleaming upon the sable carpet.
Indeed, pride goes before the destruction of Prospero's way of life, and he falls to the Red Death.