Are you familiar with community rating in health insurance? Basically, your premium is set at an average instead of being lowered if you are relatively healthy. Let's say that Jane has a high deductible policy and I happen to know that she is very healthy and her expected healthcare utilization is low. I could promise to pay her deductible (when needed) in exchange for a small monthly payment. Do the math right and she can avoid paying a big deductible while I receive more in payments than I'll have to spend on her deductible.
This product would be called insurance deductible insurance. Catchy.
Maybe there's a law against this?