I worry about this but only because I've seen so many crazy natural disasters over my short lifetime and it's a real possibility.
If "The Big One" (a large earthquake) hits the West (or East?!) Coast of the Continental United States, we will lose a significant portion of the Bitcoin network all at once. We might also possibly lose a large portion of the brain talent that is invested in this protocol.
That brings difficulty down and more Bitcoin my way! j/k Of course I would donate much of my time and money to help the victims.
If 25% of the lead developers were to suddenly disappear, I'm worried that all of the drama and tension built up in this community over the last year or two might not be conducive to getting the core software development effort back on track. We have a stellar group of individuals hammering out code and we all trust them to make good decisions for the future of Bitcoin.
It's open source. There are plenty of "Anonymous" folks out there to keep it real.
We've got some of the largest wildfires in recorded history burning right now, we've had more "mini" earthquakes all over the country than I've ever heard of before, they are polluting a large percentage of our ground water supplies with environmentally questionable (toxic?) hydraulic fracturing techniques... It is not impossible that we could suffer some serious setbacks to our community effort from within just through attrition in the next few years or decades.
There are always disasters. I don't see the connection with BTC
or any other currency. I'm surprised you left out total global thermonuclear war, now that might affect the Bitcoin Network a bit.