Health is like air, water and food. Without it, one suffers or one dies. This necessity skews the market, making health such an essential commodity that the market price skyrockets. If we allow healthcare to rise to a market level, those with money will have it and those without money will not. Not being a totally heartless society, those without money will end up in emergency rooms, with that cost being shared by everyone. And this way of managing healthcare is the most expensive. 
But people who have healthcare (insurance) are clinging to it and defending it against socialized healthcare. When they lose their healthcare or have a health emergency that exceeds that covered by insurance, I imagine they become believers in single payer. 
It seems more people will have to go broke due to healthcare costs before we see a change.