ARTPOP is not a great album, and the fan base reacted accordingly (half of them dropped off the face of the Earth or switched to Bey/Katy/Miley stans). Some people may say they enjoy it, but it will pass. PRISM is a much better album, and its' success is proof of that. People don't buy albums that aren't good (see: Pitbull's album sales, Kreayshawn's album sales vs. Adele's album sale).