In May of this year, Justin Bieber argued for his right to privacy, saying on Instagram that he was "done taking pictures with fans." He complained that he was no longer seen as a person, merely as just another famous person people felt like they could take pictures with. This is a valid concern, but as someone who attracted both fame, from his music, and controversy, from his acts of juvenile delinquency, Bieber should have recognized that he had abandoned a right to privacy long ago. When people are in the public eye, they should have the expectation that this means their fan base and celebrity commentators will take an interest in what they are doing, whether it's a new concert tour or a new relationship.
The media reports on the personal lives of celebrities for the same reason they report on hate and division, war and politics, and so on. If people want to know about the celebrities they enjoy watching or listening to, then journalists should report on it. They shouldn't violate privacy laws, though.
People who are celebrities have such fragile egos. They only care about how many likes they get on Facebook. The media should not give them this attention. If they just ignored what celebrities do, then perhaps these famous people would behave in more reasonable ways. They are only egging them on.
Celebrities are in the spotlight, under scrutiny nearly all the time for their fans benefit. What celebrities do in their private lives should be their own business and no one else's. Just because they are well known is not reason enough for the media to report on what they do off-camera. Everyone should feel free to ask someone out, shop in peace, go out to dinner, etc. without fear that the whole world will be speculating on what they are doing. Yes, celebrities have a reputation to uphold, but not at the expense of privacy in their day-to-day lives.