GPL doesn’t make you any less an unpaid labour. In fact the whole RedHat business model is about profiting off software written by people you don’t pay.
I disagree with this: Red Hat makes money off support, not taking open source code, making a few additions, and taking the whole shebang proprietary without giving anything back.
Off support for software written by someone else. That’s the point: it’s much cheaper than selling support for their own software, because they don’t need to pay for development.