WMD's are wonderful for keeping other countries from attacking (but who wants to invade Russia?), but of little use for offensive purposes.

The thing about WMD's is that you only need one.

There's no use-case for it in the modern world, except the threat of using it.

Well what if your single one is taken offline? You need at least two, for redundancy :P

1 that is actually working then :p

I believe the grandparent is talking about second strike capability. The idea is to have enough that the enemy can't destroy it all before you have a chance to react. It is possible that one is enough or it maybe that ten is far from adequate. It depends on your threat model.

Not that any of this matters if our threat model includes an enemy who doesn't care if they get annihilated in the reprisal.

Disclaimer: I don't know about any of these things and they are just guesses.

https://en.wikipedia.org/wiki/Second_strike

Perhaps that is how you, and other rational people might feel about it, but the psychopaths in charge might very well feel differently, and probably do, if history is any indicator.