Imagine that you could show up at a car dealership and have any car you wanted, and as many cars as you wanted, for no marginal cost. The market for cars would be in complete chaos, and people would have too many cars, and the ones they had would be too nice.
That is more or less the situation we now have with health care. It isn’t pretty to talk about, but if it costs $200,000 to keep an octogenarian alive for a month, someone has to pay for it. If it were the children of that octogenarian who had to cover part of the bill, and paying for that last month of life was the difference between being able to pay for the octogenarian’s grandchildren to go to college or not, there would be some hard choices to make. With health care expenditures approaching 20% of GDP, there are going to be tough choices. Markets cannot function when the people who receive the benefits of a good or a service are not the ones who are paying for it.
--Steve Levitt, Freakonomics, on the consequences of charging zero