It’s irresponsible not to have health care. So you will be “required” to have it. After all, you’re required to have automobile insurance.
The thing is, you’re not required to own a car. And you have to have auto insurance not to protect yourself but to protect others from being damaged by you. The idea, therefore, is that the human body is tantamount to a 2-ton gasoline-powered vehicle with the capacity to kill others.