Someone that received the promotional copy decided to place the album on a Torrent site. Now anyone can download your album for free and you won't see a single penny. Though you want people to hear your music, you also want to fulfill the part of your contract that requires you to sell fifteen thousand copies.
Yes, artists are given more exposure when albums hit BitTorrent sites. If the album is loved, album sales reflect this and some of the loss is recouped. Recording and marketing music isn't free, and music consumers shouldn't expect it to be.
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