If people weren't stupid they would not put up with having the highest medical costs in the world while achieving the lowest quality of care in the first world. Health Insurance Companies exist because too many people haven't figured out that their purpose is to limit, or prevent, actual health care.
Mmmm the existence of these companies is not enough to say people are stupid. Plenty of places have these companies and reasonable access to high quality care at a reasonable price. It's just the US in particular allows their companies to get away with murder.