The same thing that gives the US Dollar value. Confidence. Confidence that the green pieces of cotton can that I received can be exchanged with ease for goods and services that I need. In your cyrpto, confidence that your digital block chain can used by me in exchange of goods and services I need.

What causes inflation, the loss of confidence of the currency. Look at Venezuela. Would you exchange Steem for Bolivars? Maybe if you got 1,000,000 Bolivars but probably not 1:1