Unhappy customer

Insurance companies in general. .in the event a customer wish to cancel. .why can't a portion on the money already paid not b given back to the customer. Some pple r in these policies for years and they dnt get a cent back. .wht happens to all the payments already made. Why can it also not b transfered to a another insurance company of ur choice. Why mst the customer loose out on all tht money already paid.