A bitcoin casino works like any online casino at the tables, but its cashier is a crypto wallet address. A deposit is a transfer recorded on the blockchain, confirmed by the network before the balance appears, and a withdrawal is the same transfer in reverse. The term blockchain casino usually means the same thing, although a few sites also run games whose results are recorded or verified on chain. Either way, the casino still holds the balance while the player is playing.
Stablecoins such as USDT are popular for gambling because their value tracks a traditional currency, so a balance does not swing with the crypto market. To pay with USDT, a player copies the casino's deposit address for the right network and sends from a wallet or exchange; choosing the wrong network can lose the funds. To cash out USDT, the player requests a withdrawal to their own address and can then sell it on an exchange for local money.
Crypto casinos are popular for fast payouts, fewer banking steps and the privacy some players want. Whether bitcoin gambling is worth it is a different question, because the coin itself adds risk: a win can shrink before it is sold, and a loss can grow if the price rises afterwards. Holding crypto is investing, staking it at a casino is gambling, and frequent crypto trading on short price moves behaves much more like gambling than many traders admit.