How much would it cost a government to have a big impact on Bitcoin

As talked about in this debate at 16:15: https://youtu.be/zA5jnK4v884

Mike green argues that it would cost only 7 billion dollars to “shut down” the bitcoin network by mining empty blocks, to which Pomp didn’t really have a rebuttal.

Let’s say if the US has a lot of bitcoin and China does not, China would then be incentivised to try to break the bitcoin network and tank it’s price.