In a Medicare-for-all scenario, the individual price of a given procedure doesn't need to be so high, because the reimbursement is guaranteed. Right now, the "list" price of the procedure has to be high to subsidize the uninsured and Medicaid who lose money.
I'm sure there are single payer health insurance countries in which people still purchase insurance, which should inspire debate about the universal insurance cost-sharing.
Regardless, the only viable solution in the US is a single payer insurance model.
To use car insurance as an example, it would be like if we had a government program for cars over 150k miles. You have to pay for both private and government insurance. The private company collects more money than the government, but the government pays for all the expensive stuff because that's when cars break down. It's completely pointless.
If you want a medicare-for-all scheme where working people have a higher cost-share than children/retirees, fine, that's reasonable. Having private companies rake in profits from a system that has no business being a profit enterprise is insane.