Oh Paul!  You suggest that Aetna is pulling out of exchanges because of "vindictiveness on the part of the insurer after antitrust authorities turned down a proposed merger."  Yes, Paul, in your academic world, petty personal things rule.  In the business world, a profit is a profit is a profit.  If Aetna could make money (as it needs to to survive), it would not pass up a market.  The vindictiveness argument does not pencil out.  Shame on you Paul for being so academic.  The notion that healthcare is doing well is not entirely true.  Costs have gone up significantly as have deductibles on policies.  Look at the numbers Paul.  It is good that prior uninsured could get coverage, but Obamacare as constituted has serious problems.  Healthcare is essential and thus the industry can charge pretty much whatever it wants absent controls.  Obamacare imposed no serious controls.  A single payer, cost regulated system, is needed for this essential service.