How do you approach someone who is higher ranking about their disrespect to everyone?

I would ask a squared away senior NCO or squared away officer what to do. You don't want to be in this persons crosshairs when they obviously don't care how they treat people.

When they’re not looking, spit in their drink. Tell your friends about it later.

When I was stationed at ft campbell I had a specialist that had a superiority complex, of course I was just a PFC but I told him on several occasions that if he wanted my respect he should show me the same level of respect that he was demanding that from me but he never really wanted to show any respect to me so the only respect he got from me was the respect for the uniform