How is it more useful if >6 billion people are using the traditional system and a few hundred thousand, maybe a million are using cryptocurrencies while consuming an amount of electricity equivalent to Denmark?
Bitcoin, Ethereum etc. can be spent nearly nowhere except at exchanges because it's a pain in the ass to handle for merchants while I can pay with my Visa in the most countries seamlessly.
And how can it "bank the unbanned" when people need to have not only a smartphone but also a stable internet connection to the networks because if I don't observe the blockchain, I am still reliant on intermediates which are called payment processors in the traditional system that already exist.
Crypto currencies are just unnecessarily speed running financial history. Carried by ancaps and speculation that are only pushing it because legislation didn't catch up, yet.