If you're currently healthy, your insurance company maximizes its profits if you stay healthy (nothing to pay for except routine checkups, etc., which cost far less than the thousands of dollars in premiums your employer pays for you every year). But if you have cancer, the insurance company might maximize its profits if it refuses to pay for expensive treatments, causing you to die sooner.

Over the long run, it would seem to be in the insurer's best interest to keep everyone healthy for as long as possible.