1 usd = 1 usd
1 bitcoin = 1 bitcoin
1 peach = 1 peach
Only one of these has extrinsic value
Only one of these will keep you alive
You could die of malnutrition or poverty.
You'll need a currency to exchange for things you need, even in times of crisis, or you go the old fashion way by getting as many peaches as you can to barter for things you need.
In times of crisis or scarcity, no one will want a currency that is inflationary as that could worsen the crisis. The obvious solution is with a deflationary currency that can help curtail overspending, encourages savings and productivity.
The nice thing about currency like Bitcoin is that it work best in times of crisis. It's mobile/nomad friendly, which could allow some groups of people to settle anywhere that is conducive for productivity, and to exchange what they produce with one another either with physical bitcoins without internet or virtual bitcoins via internet, possibly connected to safe and decentralized satellite system. So, I think the nomads should always move around with survival gadgets like those that allow for satellite connections. This can help them survive better than moving around the world with peaches or fiats.