The US has regulations around banks knowing their customers and being responsible about things like this. For better or worse, those regulations have in many ways "leaked" into the regulations of other countries, because the US makes many of them mandatory in order to get access to the US financial system, which most countries see as essential.

Sure, there might be places where you could convert that Bitcoin into a local fiat currency, but then what? You have US$7.5B denominated in some random fiat currency that is likely mostly cut off from the "main" transactable currencies of the world. You'd have to find ways to slowly launder it and convert it into something else. Doable, I guess, and maybe worth the time and effort considering you can't do anything with the money otherwise, at least not without getting caught. But doing all that is risky as well... make a mistake and you could get caught.