Many foundational OSS projects use work and infra from universities. Many also use work and infra from companies that derive value from them. Partially I pay for it by buying things that those companies provide, partially I pay for it via taxes.
But for all people (inside or outside of the market) there is clearly a free beer (speech included) that you can use for personal or commercial use.
> Someone somewhere is paying even if you specifically aren't.
Someone is paying, but it seems like it is more towards "paying for the library" than it is "paying for a villa".
And in some cases there really isn't someone paying, there is just a person interested in the problem. That is surprisingly common in foundational OSS tech.