Do not forget that the money comes from "lots of work" and lots of time spent playing the game (for some, a few years already).
So, a tax with the intention of "grabbing" that money (that, in fact, is the result of time spent and dedication to the game) is extremely unfair.
It is the same, as saying: "sorry, i know you spent lots of time in the game but you can't have the money you made while playing it for such a long time respecting its rules".
I believe the (small) motivation that some users have, most possibly will turn to none (or almost to none).
This is my opinion.