I mean, how many articles and blogs are there about how to make money with foss and how many desperation and frustration is around that topic? How many games exist, that are donation funded?
I mean, please tell me, I want to publish a game, how could I make money with it with the GPL?
Selling it to only one person, who then can publish the code?
Having the code open, but serve ads or ingame purchases, rewarding addictive behavior? Sounds not so ethical either.
That leaves only donations and traditionally people do not value things they get for free. Some do and I hope their number will grow. But as of status quo the majority does not. Some GPL games I know make money, because they sell at steam and the users do not know they could also download it. Is that really ethical? What other GPL buisness modells exists?
A game is not a professional software, people would be willing to buy support contracts for.