My interest and time for music waned completely after high school, and had it not been for the ease and zero price of these technologies, there's no way I would have found the artists who produced the hundreds of CDs I've bought in that time, or the dozens of concerts I've attended.
This is just supposition, but my guess is that so-called "pirates" consume much more music and movies (paid) than non-pirates.
This gets supposed in both directions, so I would be legitimately curious about any studies that show whether pirates or non-pirates purchase more media.
You'd have to take people and randomly allow / deny them piracy. Normal Pirates are self-selected.