Linux is a marvel of the world and a large amount of its contributions have been made by people being paid to do so for commercial purposes - and I am not sure that would be true without the GPL. Is there a convincing argument there?

And outside open source there has been a staggering amount of creative work at all quality levels done for commercial purposes under the protection of copyright. Is there a convincing argument that the last century of software and music and books and etc would have been just as staggering without copyright?

I would love to hear such an argument. In my youth I thought copyright was blatantly stupid and should be abolished. I still sorta think that but I don't have a convincing argument in the face of the absolutely massive amount of good work that has been produced under it.