A majority have more than one phone. Or at least they can get a new SIM card and sign into the iCloud account. Then all passkeys are synced from cloud.

Yes, if you are edward snowden then not for you. For rest of us - it is useful

This is crazy. I have one phone and zero iCloud. I don't think I'm that unusual.

You are exaggerating. If the loss or lockdown is so bad then many would have stopped using any of icloud or google equivalent. People are able to depend on it. People are able to repair and use phones even when it falls into abyss.

Well, I mean yes. People for whom it works. Others never started.

Idk how much money you must be having, but all of my bubbles only ever go with one device

this is ridiculous. I don't even have a bubble device. Run lineageos in a decent 2020 device moto G32 for €100.

Yes, you can afford to host everything locally. Not everyone can.

A majority have more than one phone?

Or they have a laptop or tablet - even the cheapest one that has logged into Google or Apple. That way they can recover.