The logic is that if all of those things cost $50 (in reality KC's book was like $30 signed and everything and Dark Souls was $40 with a bunch of pre-order discounts) each, whichever one I pick wins the competition for my money. At that point, I no longer have the money to spend, and thus can't buy either of the other things. Even if I pirate KC's book and the film, they still haven't lost a sale because I wouldn't have been able to buy it anyway. ,That was more or less how I remember the study's logic going.
I'm not sure about your final sentence saying that you paid KC back later. Are you saying you DLd KCs book, then later purchased it, or you purchased the book, then DLd one of the other two items on your list?
If it's the latter, your logic is that you bought one item due to budget constraints, and being short of cash, you pirated^W downloaded a copy of something else you wanted. Since you didn't have any additional cash (after the first purchase), the other folks haven't lost a sale. No harm, no foul.
If that is what you are saying, then I have to call BS on that. The original artist/producer/manufacturer provides a product with the expectation that people who want to enjoy that product should pay a fee. You are saying that, since you don't have the 'fee' available, downloading harms no-one as there wouldn't have been a sale anyway.
However, you benefited from the product without paying the fee, so you got something for nothing. How is that not theft?
NOTE: If you want to argue that data wants to be free and that you should have to right to DL anything, from anywhere, at any time, the line for limitless free shit forms over there --->