Insurance is used to protect from the unforeseen and the unbudgeted.
Insurance is used to protect from economic catastrophes. It is a means of shifting risks that we cannot afford. Effective, economic insurance is not used to prepay routine expenses. In the case of Group Health Insurance, when you buy a low-deductible group health insurance policy you are in effect prepaying group medical insurance that may or may not be used. If it is not used, as is usually the case, the insurance company doesn't send you a refund.