This is because centralized casino still offer the best benefits and tournaments rewards compared to decentralized casino. Also there is only few decentralized casino that popular at this point that’s why crypto gambler still choose centralized casino since decentralized casino is not yet booming. Soon crypto user will decentralized casino once KYC becomes mandatory on all centralize casino. So far there are still some casino that doesn't require KYC which is why decentralize is still not the preferred choice of gamblers.