Re:Fiat is Effective: fiat for the crypto crowd [pdf]
by jameskegel on Monday October 16, 2017 @10:31AM
(#15483414)
These days, most of us use an exceedingly long 25 word mnemonic key; also, look into actually fungible currencies like Monero, where transactions are private by default, with the option to decrypt them for a regulatory body.
In case of crypto, the storage media containing the private keys could be seized. Failing that, the government can always obtain an injunction to blacklist your addresses to exchanges, nodes and miners as long as those operate within their jurisdiction.
You could use a brain wallet to mitigate these risks to some extent, but I doubt it is possible to put all your assets in one place and you expose yourself to the risk of cryptanalysis by torture.