Of course it is fair because it is theyre project and nobody is in this game to do charity. They should work for some kind of compensation and beying payed in tokens means that it is in theyr interest to add value to that token. In every bussines the managers board are payed better than the rest of people. The most common percentage i saw that the devs keep is something like 15%. And lets not forget that there are some costs in order to run all the operations.
So yeah, i believe that is only fair and the best way that we know that they give theyre best for the project.