the reason why BTW "flopped" or "underperformed" is because her team handled the album horribly, everything was going fine with BTW(the single) and then they had to **** it up by releasing "judas" on easter, and then they rushed TEOG and while it was still smashing on the radio during the summer they decided to release You & I, and then Marry the Night, so she released a total of 5 singles in less than a year, causing the era to have no longevity. unlike katy's smart team who let the songs smash and die out. so as long as Gaga's team make good decisions which they have so far, there is no doubt that ARTPOP will outsell PRISM.