I understand how insurance is supposed to work. The problem is that private insurance captures all of the value I pay in during my working life, and doesn't have to pick up the tab when I inevitably get old and sick.
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.
The value is that it is there. Most insurance isn't used, or ever pays back what you paid into it. That's the point; that's how it's a viable product. There's no way to insure old, sick people, that's why the government does it. It would be like selling automobile insurance only to drunk drivers, or selling homeowners insurance to people whose houses are already on fire.
There's a way to insure old, sick people (who were once young and healthy) and it's how every other developed nation does so at lower cost. How is it lower cost? the profits from the young and sick don't get shoveled to private corporations for performing the exact same function at higher cost.