You're absolutely right, it's not easy to do. But it's also one reason it's good to check with specific universities. What you'll find is that many try very hard to provide stipends, and if you help lead lectures you can even get an income. It's not unusual to net ~20k a year. That won't cover rent and food, but it's not bad!
This of course is only for research degrees. Law and medical degrees will be incredibly expensive.
So as a more detailed example, BU offers "full funding guarantee". https://www.bu.edu/grad/admission-funding/phd-funding
You would be living tight, but you wouldn't be going into debt. Many schools offer similar programs.
Skimmed other replies... What I didn't see...
This quote is actually TRUE. What it doesn't capture is that it was an intentional smear campaign. People on the left knew she was a center-right Democrat in a similar vein to Biden. But on the right, no matter who runs on the left, they will ALWAYS paint the Dem opponent as too progressive, and people on the right believe it.
That's the point.... Rather than cowing to that pressure and running people less and less progressive, run an ACTUAL progressive.