Are Americans Just Too Chronically Ill?

Are Americans simply too healthy to be sick than any other people in other countries in the world, or they simply have more access to a better health care system? If they are just too healthy, then why are there so many health insurance companies in the US, perhaps some of the largest health insurance companies than any other health insurance companies in the world? Or if the American people are just as sick as other people in the world, then do they just have access to a better healthcare system? What class of American people is sicker then the other; men or women, young or old?