[_delirium]

The issue is whether opting in is correlated with worse health. When one large company opts in, it's usually not because the company's CEO is himself sick: it's just a general policy decision to offer employees health insurance, and then thousands of people with overall "average" levels of health are non-voluntarily enrolled (the only way to opt out is to quit their job). But the decisions of individuals and small companies to choose or not choose to buy health insurance are much more strongly driven by their own personal health, with less-healthy people and people who suspect they're likely to have health problems soon more likely to buy in, and healthy entrepreneurs more likely to opt out / self-insure.