Why did Justin Bieber flip off the paparazzi?

Entertainers sometimes get frustrated or annoyed that photographers constantly follow them. Usually, most of the big stars have learned to be patient about it, but sometimes it just gets on their nerves, and instead of thinking... they just react-- whether by "flipping off" the photographers or shouting at them. Justin Bieber did flip off some paparazzi, but he later apologized.
Entertainers sometimes get frustrated or annoyed that photographers constantly follow them. Usually, most of the big stars have learned to be patient about it, but sometimes it just gets on their nerves, and instead of thinking... they just react-- whether by "flipping off" the photographers or shouting at them. Justin Bieber did flip off some paparazzi, but he later apologized.