If you get serious illness, the hospital has to treat you by law. The only question is who will pay for it. If you don't have insurance, it is almost for sure that tax payers will have to pay. That is, those of us who pay tax and health insurance actually pay double. Those who don't pay insurance takes advantage of us. That's a strong incentive for not having insurance.
In fact, the present system discourage people from having insurance because it penalizes those who have insurance by asking them to pay for the cost of those who don't buy insurance.
You may actually say only boneheads would buy insurance.