There isn't a "can't be happy" feeling to a market - just what people actually do. At the scales and volumes involved, it is literally impossible for any of those countries to divest themselves of treasuries suddenly (for one thing, bonds don't work that way).

Moreover, governments only invest in real things. The productive output of the US is a real thing because all those places buy tons of US goods and services. Bitcoins are not real things. Perhaps moreover, why would any one of those places invest in a currency at a scale which would simply let them purchase the computing power to take it over permanently?