As a software engineer, I don't sell software, I'm paid to make it. I don't even own it afterwards. I hear some people are paid to develop open source software. I don't think my career depends "pretty fundamentally" con copyright law, as if the software I produce is otherwise worthless. Most people on the planet can't do the work I do, which means that somebody pays me for this work. Changing copyright law wouldn't change this fact -- at most it could affect my pay grade.