My friend would joke about the silly things Sauron has done, that lead to his defeat. Like leaving the front door to Mt. Dum wide open or wearing the ring on the outside of his armor. I started to think about it more philosophically. Then it hit me, what if the better part of his power comes from the Ring, and not himself? What if he forged it to become the most powerful being, but at the cost of having to bend his will to that of his own creation? That would explain the arrogance, and perhaps even a secret desire of his own to be free of the Ring! Could there even be a sliver of light left in his being, that is dominated by the wicked essence in the Ring?
Think on that!