Even when the costs don't matter to an individual with insurance (though they usually do because most insurance is not all you can eat) they affect the overall quality of the whole system. For example, the U.S. delivers less care for more money overall than other nations because insurance companies, corporate hospitals, pharmaceuticals and care givers are largely not controlled in rent seeking behavior.

This means a greater share of GDP goes to pay for worse health outcomes. The cost of that lost GDP is measure in opportunity costs. That is GDP that could go to education, infrastructure, social programs or simply more savings for the median citizen.