Incentives are different. Life insurance companies have an incentive for you to not die. Health insurance companies have an incentive for you to not live (e.g. you don't that organ $$$$$$ transplant you need to live).

Health insurance is cheaper when more people are in it, not fewer. If you start offering discounts to the healthiest people, it gets more expensive for unhealthy people. So let's say the sickest people no longer have insurance. Now there's a new group of unhealthy people in the insurance pool. So you raise prices for them, and they get kicked out, too. Eventually you get to the point where insurance is not useful, because nobody needs it at all, as the insured people don't get sick. Until they do get sick, at which point they get kicked off the insurance plan. Health insurance that doesn't insure is basically fraud.

If you want to drive down the health related costs of healthcare, reduce the things that make people sick.