In your scenario bitcoin is an IOU to be redeemed. That is not the reality. Of course if that was the case and Satoshi defaulted then it would fail, but again that is not how the system works. Your assertion that the current situation is one where bitcoin is never claimed to be worth anything is false. Bitcoin is a good. People can choose to spend resources to either make more of it (to an extent) or acquire it. As long it continues to satisfy people’s needs it will continue to be valued by them which will be reflected in the price.