It is not a scam and it is the same as gold. What if gold dissapears ? What if noone wants gold anymore ?
these are the same questions. It;s just the format of value that has changed. Now we give value in a digital format since carrying sheep around sucks xP

But seriously before we traded cattle. But who wants to have them go with you everything just to trade ? How would you trade half a cow ?
So we started using things like salt and spices and rare gems and metals so we don't need to keep cattle with us. Then we went on to gold, gold made into coins then coins made from different things. Now we just using digital.