[Arothir]

I am not saying Sauron was stupid or weak. Villians often do not know everything, and what they don't know often destroys him. He probably just didn't know his being was pretty much in the Ring. He doensn't know everything. He probably didn't count on the Elves finding that he forged the Ring. So basically, it is quite possible for Sauron to think the Ring, as an inanimate object, can not truly hold a good part of his being. He merely thought he was using a lot of energy.