If you don’t know your seed phrase, someone else does - and its not your crypto! For example, if you use an exchange to hold your crypto and log in with a username/password, the exchange holds your private key. As a result, you are subject to their whims (account deletion, migration, etc). This is why crypto veterans always say the same thing - use a hardware wallet and keep your seed phrase backup locked up in a safe place. Not your keys - not your coins!
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