Single payer/Medicare for all is a wonderful program that I fully support. As far as allowing anyone to opt out of the single payer would be a really bad idea for obvious reasons. People who have annual income in the millions and billions clearly would pay millions less in private insurance premiums leaving the rest of us with a much greater burden in our Single-Payer/Medicare taxes. Especially if each individual is taxed based on some kind of percentage of annual income to pay their Single-Payer/Medicare tax.
For example, let's say someone has a annual income of $10,000,000. Let's say hypothetically that person had to pay 5% of that income into the Single-Payer/Medicare taxes. That person would be paying $500,000 annually in Single-Payer/Medicare taxes. If you allowed that person to opt out, that person would obviously opt out to avoid paying $500,000 annually in Single-Payer/Medicare taxes. That wealthy person hypothetically would only have to pay annually something like $3,000 to $15,000 of private health insurance premiums depending on what type of private plan he chooses. If you ask why is that a bad thing. That's quite simple. If all of the wealthy people, who could afford to pay more opted out, the revenue from the Single-Payer/Medicare would drop by billions of dollars. As a direct result of billions of lost revenue, the people who can afford it the least, would have to pay much much much more in Single-Payer/Medicare taxes to make up for the wealthy people opting out.
I don't know what other people think about this. I am just fine with having someone who makes an annual income of $10,000,000 to have to pay a mere 5% of his income resulting in annual single-payer taxes of $500,000. Especially when that revenue source makes it possible for someone who has only an annual income of $30,000 to pay 5% totallying only $1500 annually into single-payer/medicare taxes. Single Payer would probably work better for more people only if you do not have an opt out option especially in regard to wealthy individuals. Also, Single-Payer would probably work better if each individual's single-payer medicare taxes was based on some kind of percentage of each person' annual income. That way there would be no kind of maximum cap the super wealthy would have to pay into the single-payer/medicare tax. If your annual income happens to be $100,000,000 or better yet $1,000,000,000, your mere 5% tax will greatly help fund Single-Payer for the millions of poor and middle class all over the nation.
I would have no problem with some wealthy person purchasing private health insurance as an additional insurance, but not okay with that person being allowed to opt out of Single-Payer/Medicare