I dont think it failed as a currency. People use it daily to trade and you can use it in certain applications to purchase something. So overall it has come a long way. Its very voletile but it is also super new. So it will take a while for everybody to get used to it and to accept it.
But they actually trade them as an investment not like a currency right, because the function of a currency is about paying everthing in your life with Bitcoin or cryptos , not using them to buy other cryptos.