Medicare Advantage plans are run by private companies. I think you might be confusing Medicare Advantage with traditional Medicare.
Traditional Medicare sucks too though.
The fix for our medical system is to bring pricing down, while incentivizing innovation and not allowing your medical system to get overwhelmed by individuals that aren't contributing any money into it. You can have an argument about how to best do that but the current government backed options aren't cutting.
So your proposal is that we let the poor die?
If we're going to play this silly game of absolutes, you're envisioning a utopia that cannot exist.