senate pay controls are nice PR, but congressional members make the vast bulk of their income off the books, just like every representative body in the world. It is the nature of the beast. It always has been - the point of getting into government is to enrich yourself. What it ‘should’ be is kind of like arguing how communism ‘should’ work - it ignores human nature.
The idea is to get people who will represent your interests at the same time while making sure their nest is feathered. Looking for any other outcome is hopeless optimism, unless you believe candidate speeches.
Pay is just one of the items I mentioned. I believe states should have right of recall at any time and power to set pay because if senators truly work for the state, the state should have the powers a normal employer has. I also believe rotation in office is necessary, to limit the corruption to which you alluded.