The best argument for a single-payer health care plan is the recent decision by giant health insurer Aetna to bail out next year from 11 of the 15 states where it sells Obamacare plans.
Aetna's decision follows similar moves by UnitedHealth Group, the nation's largest health insurer, and by Humana, another one of the giants.
All claim they're not making enough money because too many people with serious health problems are using the Obamacare exchanges, and not enough healthy people are signing up.
The problem isn't Obamacare per se. It lies in the structure of private markets for health insurance, which creates powerful incentives to avoid sick people and attract healthy...