The part you are missing is that the entire system has to die for your specific data to be lost. That may happen, but it's a different risk than imagining that

The part you are missing is that the entire system has to die for your specific data to be lost. That may happen, but it's a different risk than imagining that somebody is storing a single piece of data indefinitely for a single up front fee. The risk and mispricing are socialized across the entire protocol into perpetuity.