This is not an answer. If a currency crashes, not only does that 'really matter' for most regular people who will have some material savings in that currency,

This is not an answer. If a currency crashes, not only does that 'really matter' for most regular people who will have some material savings in that currency, it also creates really terrible problems for everyone using the currency. The value of a currency is in it's integrity over time. It doesn't have to maintain perfect pricing parity etc. however, it must not just vanish and fall apart. We can see this with USD and Seigneurage with the Petrollar. People hold USDs not because they think 'it'll be worth more' but rather, they'll be valuable in the future, because USA won't crash and fall apart. This crypto stuff is mostly stupidity with bad economics all the way down. Maybe some day that will change.