I'd say as a counterpoint that just because someone works at, say, Meta or Oracle, and also contributes to OSS projects, that doesn't equate to the company they work at funding upstream projects (at least not by itself).
I don't even have to link the xkcd comic because everyone already knows which one goes here.
Everyone I know who contributes to Linux upstream is paid to do it. It's not really worth the hassle to bother trying if you weren't getting paid. It's also very easy to find companies that will pay you to work on Linux and upstream.
I don't even have to link the xkcd comic because everyone already knows which one goes here.