If anything happen to the earth then of what will then be the use of cryptocurrency? Cryptocurrency were designed as payment system,
There were lots of things already happening onto it but if you mean it will self-destruct and all man kind are going to get wiped out, I think crypto is still there on their own world or on the cyber space. If we leave them running, they can continue doing it. That being said, crypto isn't only limited from being a payment system.
so when the earth and all there is in it are destroyed, we will have more serious things to worry about and not cryptocurrency.
How can you worry when you don't have a brain anymore, lol. But if you mean if there were only wars and quakes, then yeah we are more concerned of our life than any other material stuffs ( at least for the many ) because there might be still a few that prioritizes their wealth just like what we see on the movies and usually this is the cause of their death. So that is still useless.