Responding to some of the other comments, Red Hat revenue is nearly all from providing enterprise support for completely open source software. This is critically different from "services", ie consulting. These are yearly contracts that provide clients insurance if/when they have a production issue, a new major vulnerability is disclosed, etc, that someone knows the technology from the ground up and also knows the details of their deployment and can get them back into a good state. Our support+engineering teams are top notch, so retaining customers year over year is relatively easy.
I work in Red Hat Consulting, which is a much smaller share of overall revenue. It doesn't scale nearly as well, since you only get revenue periodically for weeks to months at a time, with a lot of overhead to sell and manage assignments.
Paul Cormier has it right - "We're an enterprise software company with an open source development model". Not an open source company.
However, you're correct. Red Hat's value prop is in top notch support.