Danny: oh, I agree the sentence is idiotic. But I've never heard a reasonable explanation for the "it's not really stealing" line of thought.
The argument goes like this:
If I steal a tangible thing, in the traditional sense, I have violated somebody's property rights, because I have deprived them of property that was theirs. This is known as 'stealing'.
As you know, digital data can be copied perfectly with no generation loss. This is not a bug, it's a feature. Say that I make a digital copy of some digital data, from a copy which is itself thousands of times removed from me and the original copy that the author claims to have created. The copy that I copied has not deprived the original 'owner' of the original copy of anything. His original copy is unaffected. I have only 'stolen' from him in that
he perceives that since I copied this data, I will not purchase it in some other form, and thus I have harmed him by (he argues) reducing the probability that I will give him money. Isn't that just terrible?
This reasoning is about as solid as dressmaker arguing that if I buy a dress from his competitor (depriving him of nothing in the process), that I am less likely (he thinks) to purchase a dress from him, and thus I have 'stolen' from him.
Copyright laws are nothing but imaginary legal protectionism constructs that create artificial revenue streams for certain industries by using the threat of real, live rights violations (threat of legal consequences including theft/fines) to extort money out of citizens in the name of 'protection' from legal consequences. They pay, not the price the market has set (which is approximately zero), but an artificial, arbitrary price decided on by the extortionists, only out of their own interest of avoiding persecution.
Failing to pay the extortion money is not the same thing as theft, by a long shot. It's not a breach of contract, either. It's more like "failing to pay the price set by the person who claims the (dubious and unenforceable) authority over anyone/everyone's right to make a copy of a piece of digital data (which is really just a big number), without paying the price that HE has decided that you should pay in order to avoid him sending people with guns to drag you to court and pillage your bank account as a "lesson" to all others".