They managed to sell cryptocurrencies by proxy; maybe somebody else holds your keys, and you log in using a traditional method to have that provider use the key

They managed to sell cryptocurrencies by proxy; maybe somebody else holds your keys, and you log in using a traditional method to have that provider use the keys where they are needed or rotate and update them when you want them rotated and need to broadcast that fact. And people who can handle it themselves, handle it themselves.