I couldn't find anywhere how Graphene OS makes money.
I'm very glad we all can enjoy this amazing OS and I do realize that this is a not for profit(?) project, yet this required a significant amount of time and energy(probably?) to develop and maintain, so it would be nice to know who is paying for this and possibly why and how.
Once again, with all of my respect to such an amazing OS and a team who made this, I think it's legitimate to ask this question as it may affect both security and privacy of all of us.