The biggest concern of ftt is not really the profitability of a trader per se. What the tax concerns most is the health or even existence of an entire financial industry, its volume, its activities and etc. The majority of the trading volume on a daily basis is now generated from HFT upwards to 73% of it and if HFT won't be able to survive if ftt is implemented then the entire financial market is GONE!! It's not a question of how much less profit you will make, it's you won't be able to make money at all!! There would be no volume, no movement, no volatility, no liquidity, the bid/ask spread several 10's of cents apart even dollars apart, the market will be DEAD!! Imagine the price not moving at all from one day to another or moving very little and slippages in the amount of several dollars and forget about stop-losses you might as well wait for margin calls cuz there won't be any difference. And technical analysis will be meaningless cuz it would be so skewed and there would be so many whiplashes that there won't be any trends.
This is very likely the scenario if ftt is implemented. And moving trading into derivatives won't help because without the underlying moving, derivatives would essentially become the new underlying and if there is no movement in underlyings, there won't be any movement in the derivatives either.
If this is something that you like to see, then by all means rejoice but if not, then you know what to do. It's time you contact your Congressman/woman, Republican or Democrats to let them know your thoughts.