The best attack would be to give people the illusion of bitcoin but to take away everything good about it.
Here’s how the government could mess with bitcoin:
1) promote bitcoin ETFs to discourage people from holding their own keys and keep them trapped in the financial system
2) force all self hosted wallets to register under FBAR and to provide their tax ID and xpub so the govt could monitor all transactions
3) ban all transactions with unregistered wallets with extreme penalties. Banks and app providers would use a govt issued API to check if a wallet address were registered
4) manipulate the bitcoin price using paper bitcoin, the way that they did with gold.