The problem with play to earn however is that it encourages people to play the game to earn money instead of fun, which causes inflation to the point where it's not worth the time of a casual player to do the grindy parts of the game and instead just lay people who grind all day. This is why play to earn is terrible, gold farmers will increase currency faucets without increasing currency sinks, and it is terrible for any game with a lot of player trading.
At least for the years I played CCP managed to create keep inflation under control and markets functioning pretty well. I think the percent of players who were either buying or selling ISK was fairly low, less than 15% is my guess but there are a lot of different ways to play the game so my experience may not be representative.
