What was the reason why the Jews specifically used the substitute Adonay/Kyrios for the Tetragrammaton?

God has one name. ‘’I am Yhwh and that is my name’’ (אֲנִ֥י יְהוָ֖ה ה֣וּא שְׁמִ֑י Isaiah 42:8). In the Hebrew Pentateuch the name of God was the Tetragrammaton (the four letter) ‘Yhwh’. The Jews respected the Hebrew name of God so much to the point of actually using a substitute word for the divine name which was ‘Adonay’ (my Lord) whenever they spoke of it or read of it in the Tanakh. The exilic Jews followed this tradition of using a substitute for the divine name and they translated the name of God as Kyrios in Greek as found in the Septuagint. Kyrios simply means ‘master, owner, lord’. What was the reason why the Jews specifically used the substitute Adonay/Kyrios for the Tetragrammaton?