It's not so much that, but Bieber is simply part of a cycle in pop music that restarts every few years. There is always a marker for non-threatening young adults who sing clean songs about love. Same thing with boy bands. Its all about the tweens and their disposable income.
Oh no, I understand that perfectly, I just thought Bieber faded already. I guess he still has a few minutes left to his fame...disappointingly enough.