Laws in most countries allow for "public interest", more or less precisely defined, so even people who want to opt-out of the game are typically unable to do so. Even the UK royal family, who do often sue, are not always able to stop the paparazzi. The UK phone-hacking story resulted in a massive trial but didn't really stop anyone from hammering the likes of Emma Watson.

It does happen a lot however it's usually from celebrities who can afford to have a separation of a personal and private life. ie people who's career might be in the public eye but they're career isn't solely based on the fact they're famous (eg sports personalities, actors, musicians, businessmen of household brands).

Where as celebrities who's day job is being a celebrity (eg appearing on "reality" or celebrity game shows) need the publicity because their fame is their product. So for all but the most extreme cases, suing paparazzi would be a bit of a footgun move considering they're often dependant on that free advertising to remain in the public conciousness.

Really you know what "monstering " is some celebs think the tabs will hack your pc and upload CP.

And the tabloids killed Diana, an they're going after Her son and Meghan at the moment

Free speech and public interest laws prevent those lawsuits. Paparazzi do know where enforced legal line is exactly.