The people who have the most need for medical care will rush to be the first to enroll.
It’s like finding your barn is burning and calling the insurance company to cover it. Can it be done?
Sure, if the insurance company can charge other policyholders enough to pay for all the burning barns that will need to be covered.
In effect, we, the taxpayers, are going to be subsidizing these burning barns. And it will be sold to the public as something that a caring nation should do. (Not that we don’t already furnish public health care through local governments and charity from hospitals and doctors)
The problem will arise when you don’t get enough taxpayers without burning barns in the program to spread the cost around.
Insurance is managing risk, nothing more.
When an outside party dumps an inordinate amount of risk into the equation, and then demands the same coverage, management becomes an extinct species.