This is presuming perfect knowledge; it's a thought experiment. In this hypothetical world, your insurance company does know that in 13 months you're going to

This is presuming perfect knowledge; it's a thought experiment. In this hypothetical world, your insurance company does know that in 13 months you're going to get in a car accident that flings a 1.27mm shard of glass into your eye, that it's going to take 27 minutes to complete the surgery that fixes it, that you'll have an infection after that and the first 2 antibiotics won't work but the third one will. It's basically just pointing out that perfect knowledge makes risk 0, and that insurance doesn't make sense in a world with no risk. At that point the question is basically just whether you distribute medical costs evenly across everyone or let there be winners and losers on those costs.