How to kill Bitcoin:
In a fiat economy, where you can print infinite paper money, you buy all #Bitcoin, slowly and steady. No more to use because all is locked.
Is it economical feasible? No, but who cares if you can just print more paper money?
Discussion
This doesn’t work in practice I’m afraid. Aside from the fact that a state actor could never buy all the bitcoin (I will never sell any), any that they effectively remove from circulation only acts to increase the value of the rest.
Coordinated state actors. Even if you dont sell, you can never create an economy with some thousand Bitcoins.