Except the value of insurance isn't subjective from the perspective of everyone else. If one of those "reasonable, rational people who did not purchase health insurance" gets hit by a bus and has the good luck to survive, then almost certainly it'll be everyone else paying for their treatment in one way or another.
Only because some folks insist that society pick up the tab for people who make bad decisions. Some of us would have a society that says "oh, you didn't buy insurance and now you're really sick? That's a bummer. What are YOU going do to save yourself?"