$174K Congressional salary ($14500/month) is nothing to sneeze at, but with median rent being $4480 in NYC and $2549 in DC, she'd still manage to be "overburdened" (i.e. spending more than 30%) on housing costs.
Although I know I (being a FIRE type of guy) could max out tax-advantaged investment space ($23K 401k + $7k IRA = $30k, or $2500/month) from the $7k/month left over after housing, I don't know what other high expenses a Congressperson might have that could make it harder (lots of travel costs, etc.).
Not to mention that the government takes 24% of that in taxes, and she might be paying income tax in two different states. Add on sales tax and POOF, there goes half her money.
She makes 147k and lives in the Queens/Bronx where avg rent is ~2000 for 600 sqft and also has to have a place in Washington DC where average rent for a 1bd 1ba in ~2300 for 700 sq ft. She probably pays above average in for a larger place due to her job so let's say 2.5k in her district and 3k in DC. After tax she has 1.85k/mo to spend on non-rent expenses including her student loans.
This is all napkin math and while she also probably has some paid speeches her overall budget after 2 rents isn't too different from an average college grad without family help even if she makes decent money.
The most telling number is the 401k one. If she was the wealthy sort, she'd probably be exploiting that sort of thing as much as possible.
Or maybe not, because she knows it will be in the disclosure. But most wealthy people follow professional advice on how to pay the least taxes, and that includes exploiting retirement fund tax breaks.