That doesn't surprise me at all. Being a legislator is a full-time job that's not always paid accordingly, and can also come with a bunch of extra expenses associated with it. Like, a US Representative has a bunch of travel expenses and public appearances they have to make as part of their job. That's a bunch of money they have to spend out of their own pocket. National legislators are paid pretty damn well, but I'm sure a good chunk of that is taken up with expenses they're only incurring as part of their job.* People who are independently wealthy will have a much easier time running for and holding office.
It's even worse at the state level. Those salaries range wildly
from a high of California paying a hundred thousand a year, down to basically nothing. New Mexico pays nothing, but does give a $160/day per diem. New Hapshire pays $200 for a two year term, with no per diem, and has four hundred freaking people in the legislature. Even if I wanted to run for office, I'd have to be able to do that while either not needing to work, or with a job that allowed me to do my legislating. All of that's almost impossible to do unless you're wealthy enough to not need to work full time, have a home arrangement that allows one partner to work and the other to legislate, or to be retired.
*Note that I'm super not saying "oh, those poor congresscritters are paupers on their hundred and seventy-four thousand a year salary. I'm just saying that it's not as clear cut that their salary scales in the same way it would if I suddenly made that much.