What are we supposed to be "stealing"? Information is a mental construct that humans use to make an easier sense of the world. It's like a component of PCA. Or some tree in a random forest classifier. It's not an independent object existing "out there". (Unless you believe in platonic objects: in which case you need to bring evidence to court to support your — apparently — religious beliefs.)

Information is just brains. And brains are already owned by minds/souls occupying/generated by them. The same goes for hard drives, DVDs, USB sticks, individual DNA molecules, etc. You can only "steal" information by stealing a brain or an actual USB stick. The same goes for "owning" it. (I will grant you that unauthorized access is a crime of trespassing, but in most cases copyright violations are not that.)

tldr: You can't just invent an imaginary category that you pretend is ownable, in pursuit of some social goal, and then threaten to put other people into a rape cage if they don't follow along with your fantasy. Well, you can, but that would make you an immoral bastard™.

[Analogy:

Look, imagine someone comes to court and says that he's suing his neighbor for blocking his driveway for an hour. He is asking for $1M damages. The judge asks what the damages are for, and the plaintiff answers: "For the death of my pet and resulting emotional suffering."

The judge asks: "Which pet?" The plaintiff says: "My imaginary invisible unicorn." How well do you think that would go?

Now imagine if the plaintiff admits that he actually doesn't even believe himself in the existence of the unicorn but just wants to invent his existence as a legal fiction to deter blocking driveways.

In case you didn't get it, this was all analogy for intellectual property. Downloaded from my imaginary platonic farm.]

"That they can profit in this way provides an important incentive - aside from the intrinsic value of the productive activity itself - for them to engage in socially useful productive activity."

That's just it. This is a business model built on threat of violence and coersion that provides additional incentives over and beyond what content creators would get without it. Just because a business model is able to collect money - extortion, say, or confidence games - does not mean the model itself is ethical. The argument that we need to keep the existing incentives in place is much like arguments made by any other entrenched interests who are getting the benefit of some societal system or government program and want to continue it because - to hear them tell it - the repeal would make the sky fall.

Even if it leads to ever increasing absurdity like the USA endlessly extending the age of copyright to prevent works from falling into public domain, or the software patent race and sunk costs in buying porfolios, leading to speculative legal fishing for money.

The history of SCIENCE, open source software, and freely available wiki sites show that people will contribute content and create great and useful collaborative works even in the absence of monetary compensation and business models that coerce people into paying. In fact, even the question of ego / attribution seems to be answered - people don't have to get "top billing" in a movie or be listed as a book's primary author in order to contribute. And the result is often better than a commercial enterprise, for a variety of reasons. It evolves with time, is accessible from more environments, and leads to more wealth creation in the long run around it. The internet protocol suite, linux, webkit, wikipedia, publicly accessible science, all of it.

The human motivations are very well explained here:

http://m.youtube.com/watch?v=u6XAPnuFjJc

It is somewhat ironic that anarcho capitalists decry government for using force and then ask for more of it to protect capitalism and property, in areas where a naturally occuring gift economy without coersion and which confers basic freedoms on all users has been shown to do better. This irony can be best seen in the way every anarcho capitalist switches from deontological arguments (what is moral in and of itself) that they use to criticize systems of government, to consequentialist (what the outcomes would be) as soon as the time comes to justify the use of force to maintain property and incentives of capitalism for something. "But think of all the great movies that wouldn't have been made because no one would have any incentive." Yeah, and think of all the crimes that would have been committed if no one would have government.