Everything we add value to is nothing more but a social agreement.
Bitcoin, Papermoney, Gold, Silver. We give it value.
And just because a authority (goverment) is watching over it does not make it more real than something like bitcoins.
Noone can give you a guarantee on a value of something. The market is controlling it. And this market works in the same way for everything.
Doesnt matter if papermoney, bitcoins or trading cards in elementary school.
The one guarantee you have with gold and silver is that they had a constant demand over all the ages of mankind.
But so were Seashells at one point in the history of the human race.