Even the high number assumes that every person that pirates something would have purchased it had the pirated copy been unavailable: common sense should let you know this isn't true.

I probably purchase more media because of file sharing. I'm not going to blind buy all of my records. Also, I never really understood the term "piracy" being used to describe file sharing. A pirate doesn't board your ship and magically duplicate your cargo before leaving with your goods untouched and no one walking the plank.