I think their bunker won't run out of exotic luxuries until after they die quietly and comfortably in their sleep.

That's because they know that fallout type scenario wont happen. Things will broke apart year after year. It's not coming hardly enough during their lifetimes and they already own enough to be protected from nearly everything (like, some islands).

That's what Romanovs also thought.

They might rest on their experience that, if it comes to it, they're going to be the ones doing the worst to other people.