I work at a proverbial large, conservative, midwestern state university. Part of my job is to nail people's heads to the floor who are illegally sharing protected IP. It's a pretty big problem, as you can imagine. Not only from a legal sense, but also from a sysadmin point of view, as we need to backup data stored on univeristy machines, etc...
Anyway, in my experience (and only mine, your mileage may vary), most of these jokers downloading mp3s, dvd rips, textbook scans, and RPG scans/pdfs are simply horders. I've seen hundreds of gigs of stuff, all neatly sorted into folders, just sitting there. Seriously, we sat down and figured out this one dude had over 2 years of movies and music to watch and listen to, if he listened for 12 hours a day, 5 days a week. He had over 20G of RPG stuff as well.
Now, I have to wonder, to what purpose? I think the "thrill" to these guys is the actual finding stuff, downloading it, and checking it off of a list. I seriously doubt these guys have time to play RPGs because they spend so much time hunting around and catalogging what they have.
So I'm dubious about two arguments:
1) People download on a "try then buy" basis. I don't think they have time to "try" out this stuff.
2) Lost sales. Like I said, I don't think many of these jokers have time to read and play, so why would they buy it.
I really think most of the people with 10s or 100s of gigs of illegal RPG stuff are actually just packrats. I really don't think they use it. They just keep buying bigger drives, blank DVDs, and LTO drives to back up there collection, never having the chance to use 1% of it. Guess the joke is on them.