According to my oopinion, each country has its own economy and its currency, confirmed by a gold reserve. Digital money cant become a single world currency, because they are decentralized in the world
Such a volatile currency, as Bitcoin can't become the main world currency. People can't receive salaries and social payments in Bitcoins with the risk that their incomes will decrease overnight, for example, by 10-20%. Regulation of the crypto market will devalue the whole idea of cryptoencryption and blockchain.