I believe the vast majority of people who work in Open Source graphics are actually employed to do so. There are very few people working without compensation, and once they do a handful of meaningful contributions they get offered jobs. We should be actually thankful to the for-profit companies sponsoring those people instead of investing in more closed-source stuff (Intel, AMD, Collabora, Igalia, Red Hat, Code Weavers, VMware, and a few dozen of others I am missing, heck even NVidia contributes to Open Source graphics, although not as much as we would like them to).