In my country (Australia) ALL gambling winnings and profits are 100% tax free.
You don't have to declare it because it is considered a hobby.
In the USA and other countries gambling winnings are treated the same as income and gambling companies are required by law to withhold federal income taxes.
If I had to pay taxes I would quit gambling. The risk wouldn't be worth it.
Does your country tax gambling winnings and if so do you declare it yourself or does the gambling operator withhold the taxes on your behalf?
Your government may not need additional taxes so they prefer not to tax its people because the Australian economy is robust, but other countries are not that robust they need additional funding so instead of resorting to borrowing from local and international banks they prefer to tax the gambling sector.
I have seen how taxing the gambling sectors can do to one's economy because I'm living in a country where so many things are being taxed, and gambling is one of these.
Our country takes 20% of the cut in the winners' winning besides different taxes within the gambling sector, our government is good at collecting these taxes.