[MarkCole]

I'm fairly certain it is. Billionaires and their families are at a high risk of being kidnapped and ransomed. Then there are stalkers, and obsessives who might try to enter your home and endanger you and your family.

I imagine as CEO of Facebook he probably receives a lot of hate mail and possibly threats. Better safe than sorry.

Zuckerberg is also quite a private person (as you can probably tell from him buying up surrounding homes to distance himself from the neighbours) so scaring off journalists and paparazzi is probably an intended effect of his security detail.