The second piece is that M4A is a huge unknown, and so they'd want to keep their health insurance because they're afraid that what the government will offer will ultimately be worse.
The first point is certainly easy to address as that money would then likely be renegotiated to result in salary increases, but with regards to the second, what would stop a republican administration from doing things like, effectively banning abortion by refusing to pay doctors who perform them through executive order.
Basically I think no one expects it to get better, so they are just all hoping it doesn't continue to get worse (while expecting that it will).
I had to tune out after that part of the debate. Watching a bunch of candidates, and especially the frontrunner, claim not that MFA was OK but their plan was better, but that MFA is some kind of impossible dream that can't work, just pissed me off too much. Screw them. Seriously.
The refrain of "people like their health insurance" deliberately conflates the two. People like their doctors, not their insurance. Doctors accept multiple insurance companies.
Some do, but not all. One of my providers takes exactly one insurer, which I do not have, so pay out-of-pocket.
Luckily most insurance companies allow you to submit receipts to receive credit towards your deductible.