@mwl @Corvan Sure, but that’s not stealing. Stealing is normally when you take something from someone; you gain it and the other person loses it. Making a copy is very different in nature, since the other person does not lose whatever you take. Even if it’s a bad thing to do, and the other person still loses out on profit, it remains different from stealing. I think the difference is important enough to avoid conflating the concepts.

Your argument makes perfect sense if we assume that each creator has the final say in how their work should be used and shared. But not everyone agrees on that; for instance, some hold the opinion that every work should be free to use and share, and they value this belief over the author’s decision. It doesn’t really make sense for these people to firmly follow the author’s licence, if it directly goes against the idea of how software or culture should be. They would be betraying their own beliefs if they did that, wouldn’t they? Yet it does make sense for them to be in favour of copyleft licences, because those support and propagate their idea, rather than work against it. Copyright is not something they inherently care about, but rather something that can be useful at times (and obstructive at others).