Redhat supports the community by providing tons of maintainers/maintenance of projects. So, they may not support $PROJECT with dollars, but for a few thousand projects they base their business on, they provide hundreds of thousands of dollars in year in engineering time fixing bugs, or updating things which are bothering their customers. Particularly on all the unsexy portions of the OS that everyone else has moved on from.
'Maintenance' sounds like a takeover without compensation. Surely with $3 billion in revenues Redhat should have a open source fund to sustain people whose code they use? Shouldn't some money find its way back to all the open source projects?
Red Hat (and SUSE, Canonical, etc) also employ a lot of upstream maintainers to continue doing their job. That's a much more sustainable model than having companies donate to upstream.
