That's not true, because most people do have insurance. The major problem is that the costs are socialized by insurance, so people buy excessive healthcare because then can afford it (they aren't paying).
There are other countries where everybody has insurance and the government negotiates medical prices. Japan, Germany, and France are three examples. They have much lower costs than the U.S. and the best health outcomes in the world, measured on criteria like death rates after diagnosis of major disease.
Source: Healing America by T.R. Reid.
And Japan, for example, has an aging population of heavy smokers.