Yesterday, I had to take a client (teenage girl) to the Monroe County Department of Health to get her vaccinated so she could go to school. The place was packed. We sat in line for 2 hours to get our number called. After that we had to wait another half hour to get her name called to get in. To get the shot, literally took 30 seconds.
During this time, I got to watch people of all creeds and colors who just wanted a simple, health-preventative service, some of whom were migrants. If there were single-payer health care, these families could have done this in numerous places and different times. And I'm pretty sure that more people would be vaccinated as well.
You can look at this two ways. Single-payer health care is morally right. I don't care if that "right" is in the Constitution or Declaration of Independence. We are supposed to be a civilized society and basic human needs should be taken care of.
Another way to look at this is more pragmatic. If we make sure that everyone has the basic necessities of life (food, clothing, shelter, health, safety) we will have less need for other social services due to improved conditions for people who use tax-funded services. Less taxes! Think of it as trickle-up humanism.
You don't want to pay for someone else's health care? Fair enough. I don't want to pay for your war. I don't want to pay for your corporate welfare. Or your theater, or the police or fire department who are in your section of the community and not mine. See where I'm going with this?