A system under which healthcare costs are shared throughout the community, rather than being dumped on one person. Has a couple of big advantages: first, checkups and tests, even advanced ones like MRIs, become much more affordable and more convenient when you don't need to involve the insurance companies. This lets people catch and treat problems earlier, making things cheaper and easier all around. Second, the overall cost for procedures is cheaper.
Under the US's private insurance system:
Dental work, $2000
Ingrown toenail surgery, $200
Under Japan's universal healthcare system:
Dental work, $160 upfront
Ingrown toenail surgery, $14 upfront
You're telling me that instead of contributing a bit to a group pot, you want to pay obscene amounts of money to a guy who might pay SOME of your bills if you get hurt... if he feels like it, and decides it's worthwhile? Whatever, man. Whatever.