Do you mean general fiat gambling or crypto gambling? In my country, both have different sets of rules and taxes imposed on them. In my country, both fiat gambling and crypto gambling are illegal, hence I can tell you about crypto gambling taxes. If you withdraw any cryptos into your bank account, they impose tax on it. They don’t see generally from where you get the coins from. They directly impose a 30% tax on the total amount you withdraw. Whether you lose money or make money in crypto, they don’t care about it. They just straightaway put the taxes from the amount. I live in an Asian nation.