Bitcoin has remain the only cryptocurrency that has been recognized globally but secretly been reviewed and monitored by governments and financial institution. i think Bitcoin still have a long way to go. fiat usage is simple and easy. without the usage of computer and internet, there is no way someone can use or send bitcoins. with or without the internet, people can make use of fiat for payment of service. Most adults are not computer inclined. adoption requires more time.
Also,i think bitcoin and ethereum are the most popular cryptocurrencies available. the rest are just subordinate.