The notion that people will wait days or months to settle survival transactions after a catastrophe is absurd. As is the notion that after major global collapse there will be a robust global network so that planetary consensus can be achieved. Ditto that enough people will care about global transactions when global trade falls apart.

Bitcoin can't even build a significant user base now. Approximately nobody buys anything with it. Compared with debit cards or cash or mobile money systems like MPesa, it's a rounding error. If it's not better than any of the existing payment systems, it's not going to get better in some sort of prepper-fantasy collapse.