First of all....Impressive amount. Congrats 
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If it is an amount that is in $ or EUR, then that is impressive, and if it is a local currency in which millions do not mean a great fortune, then the OP is not one of those who can not say that he got rich on sports betting
This fella isn't back to answer the questions that people need to give the best answers, like Where are you from OP? This is very important to know because you can be from a country that doesn't care about paying taxes on gambling, there aren't many countries that ask gamblers to pay taxes.
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He was online a few days ago, but maybe he was just too busy spending his winnings
Joking aside, such things are best clarified by visiting the local tax office. Everything else is just speculation, considering that we don't know where the OP is located, possibly even in a country where cryptocurrencies are partially or completely banned. There are always ways to sell crypto without paying taxes, whether it's p2p or virtual cards, or maybe even paying for goods or services directly with cryptocurrencies.