Why is the devil called Lucifer?

Why is the name Lucifer only found in one place in the Bible and why has that name been associated with the devil? We have all done it and not even realized it? Isaiah 14:12 in its correct context is clearly referring to King Nebuchadnezzar of Babylon, and comparing his fall from power to that of the rise and fall of the morning star, which is the wandering star (not planet) Venus. This was a difficult correction for me to make in my process of thinking. I have made videos of Venus during sunrise and sunset so this makes sense to me. You can view those on my amateur astronomy channel if you like.
https://rumble.com/c/c-1702522