Red Hat uses a very similar business model providing managed enterprise features on top of open source.

What software programs or features does Red Hat not make available under a FOSS license?

There are a small handful of exceptions. Many were in the exactly the right place at the right time. That’s not a repeatable strategy. I wouldn’t start RedHat today.

They’re called “IBM” now.

They wouldn't have gotten acquired by IBM if they couldn't make a profit.

IBM could use the Red Hat Enterprise customer base to sell consulting services to. If the projected profits from consulting is large enough, no profits from Red Hat is needed.