You hold it if you want to use the money to trade crypto, because banks really don't like you moving around large amounts of money. So you hold USDT in a walle

You hold it if you want to use the money to trade crypto, because banks really don't like you moving around large amounts of money. So you hold USDT in a wallet instead of transferring it back to the bank. It's also a lot faster to transfer money using stablecoins then it is with banks.