The goal is not to make it impossible to use crypto but to make it so untrustworthy that nobody wants to touch it. Host mirrors of popular software wallets with hidden malware. Add backdoors to some hardware wallets at the factory. Create trojans that sit quietly and harmlessly until you try to deposit your coins at an exchange, at which point, unbeknownst to you, your compromised browser is displaying the CIA's bitcoin address instead of the exchange's as the place to send your coins. Make smart contracts with increasingly clever obfuscated time bomb backdoors. And it all comes with easy plausible deniability, since any of these tricks could just as well be regular old crypto thieves, highly motivated by the massive "bug bounty" on any exploit, including social engineering, that lets them steal coins.
Of course, the backlash if this was ever found out would be immense. It would basically be the US government operating a cybercrime organization. Many of the victims would likely be US citizens speculating in crypto. It wouldn't be worth it unless the powers that be decided crypto is THAT dangerous to the status quo.