My problem is that if the crux of your (or anyone's) argument that everyone should buy insurance is "Well, EVERYONE will have an expensive disaster/medical diagnosis within a few months!!", then that's demonstrably false. Indeed, it's not even true for the vast majority of the population, and it's not true with that regularity - for example, a person hit by a car may incur expenses, but it likely will only happen to them ONCE in their lives, not with regularity every few months.
If the entire basis of your argument is founded on something that is FACTUALLY, demonstrably WRONG, how can we take your argument or its conclusion - that people are just accidents waiting to happen, that these accidents WILL happen, and thus everyone should get insurance - as a valid or worthwhile argument?
When the foundation of the argument is just WRONG, then the argument can and should be rejected.