because the bitcoin is already created as a virtual or digital currency that can not be used as a legitimate currency. therefore bitcoin will not be used as a legitimate currency because not all countries that legalize bitcoin in the country
Most countries still haven't legalize or accept as a currency and and yes one reason is it is a digital currency and unlike fiat money it cannot be controlled or traced via centralized authorities but still no one can say it will happen or not and the time is the only thing can decide that but there is a big possibility if majority of countries and banks accept Bitcoin even as an international currency beyond the formal path Bitcoin will be considered as legit.