The standard "model" is corruption in US campaign finance is about politicians collecting money to get re-elected, as if getting re-elected is the only thing that motivates them. Or, slightly more broadly, the money lets them be kingmakers - I rise through the leadership ranks by supporting other House members who then repay me with their support.
Of course these operations support a much bigger range of dubious if perfectly legal salaries and expenses. Quite clearly people are finding ways to line their pockets, and that of their friends and family.
A small example Sinema using the cover of fundraising to pay for trips she wanted to take.
But really I'm sure that is a small example.
I bet it's the family business for a lot of people, and it's the kind of "corruption" that goes underreported because it's the family business for a lot of those people, too.
The grift has long been central to conservative politics, but it seemed a bit more arms length from the electeds themselves. And not just conservative politics.