> a nation-state. Let's say the US, EU, or China decided for some reason that it was in their national interest to blow up Bitcoin

Irrelevant and impossible to "know", given that it hasn't happened yet (if it ever does)

They could borrow 1 Billion in Monero and sell it. Then they would only have to pay back a fraction and keep the rest.

Imagine if you will that the Russian economy ran on Bitcoin or whatever.

75 million a day to destroy the Russian financial system is less than half of what Ukraine currently spends on their defence budget.