Surely one of the great dividends of being at peace is not having to live like you're at war?

We’re not at nor heading towards peace. Pax Americana is failing. There isn’t a hippies-and-unicorns exist from that structure, not in a disorderly way.

I didn't realise only people at war used cash

Rather the opposite. Peacetime is the only good opportunity to promote robustness and refuse toleration of vulnerable systems.

If you allow your banks and courts to be hacked freely by an adversary, then you can be manipulated into losing control of the escalation ladder.