The current capital gains tax for buying US and Hong Kong stocks is the same as the lottery. The tax rate is also the same 20%. Your capital is 1 million and you earn 10 million. Then it falls back to 1 million. If 1-10 million is a full year, now no matter whether you lose it all in the subsequent year, you have to pay 20% of the 9 million. You bought a lottery ticket for 2 yuan and won 5 million. Then you have to pay 1 million in tax first. As for you buying a lottery ticket and losing 5 million later, it has nothing to do with tax settlement.