Throw in gnawing dissatisfaction with the pay and disgust with management hostility and abuse... VOILA... the guy will GROW UP!!
If he played his cards right, he'd never have to work another day in his life. Or he can surround himself with a bunch of jobless thugs helping him burn through his fortune on mansions and Ferraris, designer clothes and jewelry and he most certainly will have to find work again.
The transition from teen heartthrob to adult stardom is a difficult one. For every Justin Timberlake there's a hundred others who's fame has faded away and who's money vanished. The entertainment industry chews these kids up and spits 'em out. In a few years, Bieber will be "long in the tooth" at 22-23 years old and there will be some other fresh-faced teen waiting in the wings to take his place.