nostr is like email or the world wide web. it can't go down. certain email servers or web servers can go down - twitter was down earlier - but nostr as a protocol can't go down. just like email or the web, certain nostr websites or relay servers could go down, but dozens, hundreds, or thousands of these could still be running just fine. that's the difference between a centralized service and a decentralized service. this is what all of us need to help our friends, family members, and random people on the street realize.
Discussion
Perfect explanation.
Bitcoin too. Everyone has their own keys, they create their own transactions and they broadcast it to any number of bitcoin nodes online (or otherwise -- e.g. radio, satellite, bluetooth.)
Lightning not the same unfortunately. You rely on a particular node and the interactivity of a particular party. Lightning in general works, just like saying "banking works, but PayPal is down". At best, the unilateral exit makes it "still bitcoin".
But still, this is power: having a money that is robust and NOT dependent on a single point of failure. Not only does it not rely on a particular form of infrastructure, but it also is not founded on a changeable law, it is not tethered to a country, it just is.
How would Nostr relays stand to ddos attacks?
an attacker would need to attack 1000 different relays at the same time across numerous geographical regions and data-centers and ISPs to effectively kill nostr. that's not easy.
Decentralized open communication protocols are so necessary!