Paper currency is dirty and is a major transmitter of disease as it goes from unwashed hand to unwashed hand. It is easily lost and stolen, and can be easily destroyed by getting wet or burned. It physically wears out in a short time and is costly and troublesome to replace. So why do we still use the filthy stuff in the electronic age? It's called "diversification". It's far easier for thieves to to electronically steal all of our money kept in one mason jar ("bitcoin") than it is to for them to dig up a million mason jars in our individual backyards.