Why would Sauron make himself a ring? wouldn't it be better to keep the power in his physical form and not risk leaving his power in a physical form that could be stolen like Isildur did. Because of its being in the form of a ring, its power could be abused by someone else to attack him.

Why would Sauron make himself a ring that he invested most of his power in? Wouldn't it be better to keep the power in his physical form and not risk leaving his power in a physical form that could be stolen (which did happen when Isildur took it). Because of its being in the form of a ring, its power could be abused by someone else to attack him.