The ACA does mandate insurance, but the point here is that the law depends on healthy 18-34-year-olds signing up on the new public exchanges such as Healthcare.

The ACA does mandate insurance, but the point here is that the law depends on healthy 18-34-year-olds signing up on the new public exchanges such as Healthcare.gov and state-by-state sites. Right now a higher-than-expected percentage of people using Healthcare.gov are elderly or chronically ill people who had difficulty getting private insurance. If the insurance pool is full of people using the insurance, the premiums will go up, the insurance will be considered expensive, and fewer healthy people will choose public insurance, kicking off a vicious cycle.