Under Obamacare, insurance companies would be barred from denying coverage based on pre-existing conditions. Most people think this is basic fairness, since they assume pre-existing conditions result from bad luck.
In some cases, this view is correct. People born with genetic diseases like Huntington's corrhea or hemophilia did nothing to cause their conditions.
Yet many pre-existing conditions result from decions made by those affected. High blood pressure and high cholesterol are often due to bad diet and lack of exercise. Most lung cancer is caused by smoking. Cirrhosis of the liver reflects excessive drinking.
So it is far from obvious that fairness means people who have insurance should pay higher premiums to fund health insurance for those without. Instead, fairness would seem to dictate that those who contributed to their own health problems should bear the consequences of their decisions.