They wouldn't. A lot of cryptocurrency justifications hinge on made up scenarios. They also ignore the fact that it costs money to even send or spend most cryptocurrency, or the fact that it must be liquidated in 99.9% of spending scenarios, and ignore the challenges in buying or selling cryptocurrency in the first place.

Most exchanges require several forms of ID and verification to buy or sell cryptocurrency. I had to use a smartphone to take a picture of myself with my photo ID before I could even use most exchanges. Someone who doesn't have photo ID, computer or a working smartphone are out of luck in that scenario.

Bitcoin might make sense for remittance, with the intention that it is then liquidated after being received.