Or maybe I'm completely wrong in this assessment.

But... what use case value can it have if not as a means of payment of last resort?

Here is my Bitcoin Paradox:

The only real use value it has is its exchange value, not the other way around.

Since it's neither equity, nor credit, nor a commodity, nor another means of production. It doesn't shine, you cannot wear it, you cannot fire it, you cannot eat it.

It's the perfect money as long as it becomes/remains money. Otherwise it's useless.