No one smart uses Medicare, instead they use Medicare advantage, which is private health insurance funded by the government.
This is the part people don't understand when they promote Medicare for all - it's a really really bad plan, that people don't use unless they have no choice.
This should be the death nail in these proposals, except the people proposing it typically don't even realize the difference.
Medicare for all is a horrible idea.
Government funded private health insurance for all is a good idea.