However, none has been able to fully improve all three functions in a superior way, owing to their instability. Digital assets are not widely used as a medium of exchange; instead, they are mostly employed for speculation. Those that are more expressly designed to function as a medium of exchange have had a limited level of adoption. There simply hasn't been enough value, ubiquity, or convenience of use to encourage mass adoption. Most digital assets have much too much volatility as a unit of value to be considered an upgrade over many traditional fiat currencies. Bitcoin has traded at a high of $66,804 and a low of $5,032 versus the US dollar in the last two years.