The thing to remember is that anyone who knows your seed phrase can access and take your cryptocurrency. It's crucial that you store your seed phrase securely so that only you can access it.
Seed phrases explained
Unlike a bank account, cryptocurrency isn't tied to your identity. It's stored on a blockchain, which is a ledger that records all the transactions that occur. To access cryptocurrency, you need to demonstrate that it's yours by providing a password.
The seed phrase is the master password to all the cryptocurrency managed by a wallet. It's worth noting here that wallets don't technically store cryptocurrency. They provide access to it by storing the keys to the funds, which are used to access that crypto on the blockchain.
Seed phrases are needed because there's nothing connecting people to the cryptocurrency they own. If you lose your debit card, you can ask the bank to send you a new one because the account is under your name. Blockchains don't have your identity, so if you lose your blockchain wallet, the only way to prove that cryptocurrency is yours is with the seed phrase.