If the GM wont pay 10 dollars to help a charity then that just reaffirms their cheapskate status. In other professions the high level participant would be ashamed and embarrassed if they refused to help out. Often it's the complete opposite, the people at the very highest level pay even MORE than everyone else because they want the perception of helping more, caring more. Which in turn motivates more people to also help out or participate.
Maybe GMs have spent so much time playing chess they haven't learned the social skills necessary to recognize when they should be embarrassed. I don't know, but either way it's not a good look.
I don't doubt it's common, I just don't understand why. Why would the players who have the best chance of winning not have to pay to enter?
The GM status attracts players, more players, more money overall. Why does Tom Brady do the "Let's Go" Hertz commercials?
In the end, they get more money. Why do we have to pay subscriptions on Twitch to play GMs, but the GMs don't have to subscribe to us? Same thing.
I don't know, but it does make them look like cheapskates. Of course I would never pay money to play a grandmaster because there is no value in it for me. But that's just me.