All currencies, digital or not, big or small, continuously lose and gain "make-believe" value in largely unpredictible ways (see forex markets). Some are stable

All currencies, digital or not, big or small, continuously lose and gain "make-believe" value in largely unpredictible ways (see forex markets). Some are stable (EUR). Some are volatile (BTC). Some die (German Papiermark, Zimbabwean dollar). Some live longer (GBP, JPY). Some lost value in the immediate past (USD). Some gained value in the immediate past (BTC).