Ethereum is the blockchain that added programmability to the Bitcoin model: it can run smart contracts, and it is on this foundation that most tokens live, including USDT in its ERC-20 form.
Why it gets expensive at a casino
An Ethereum transaction fee is paid as gas and its price is an auction: when there is a lot of activity on the network, the fee rises for everyone at once. A token transfer invokes a smart contract and consumes more gas than a simple ETH transfer, so **sending USDT costs more than sending ETH**.
In practice this means a 20-euro withdrawal on ERC-20 can leave you with 14. The same amount on TRC-20 would cost cents.
Two things to remember
Sending a token requires ETH. USDT alone in a wallet will not move — gas is always paid in ETH. A wallet holding only a token is locked.
ERC-20 and BEP-20 addresses are indistinguishable. Both start with 0x and are
the same length. The format does not tell you the network; only the source of the address does. This is
the commonest cause of a wrong-network mistake.
When to choose ERC-20: for larger sums, where the fee stays small as a percentage, or when the recipient simply supports no other network.