Missing shipment

I recently made a purchase for $860 for a used item from a private seller. The seller shipped USPS Priority Mail. USPS tracking says that it was delivered. It was not by my door that day or for the next 3 days. This is the very first time in my many years of buying/selling that a package has gone missing. I live in a safe neighborhood. The seller did not insure it. We did not discuss insurance. I assumed that he would do so since $860 is a significant sum. He has 100% positive feedback – as do I. I’ll be filing a ’missing mail’ report with the USPS in the hopes that it will be located. But, since it wasn’t insured, will I be stuck with this loss?