Therefore, traders should find a logic with robust adaptation to many countries, in case his/her country's tax rate is increased suddenly.
For example, if one has a trading logic with 30% (before expense),
1) under 15% expense(tax+commission) his final rate is 15% roughly
2) under 25% expense annually, his final rate(to bring home) might be only 5% (close to bank interest)
For the 1) tax rate is 50%(expense/originalreturn), however 2) tax rate is 25/30 = 0.8333333 >80% which is (almost) meaningless to do.
Personally, I can say "Trading is against other traders, also against expense as well".
Never say "I am broken now since I put all the money to Fukushima"