Both are successful, so I respect them as (arguably) clever businessmen. That being said:

Justin Bieber's existence has no negative impact on me whatsoever, when he annoys me, I simply stop listening to the crap he unleashed on humanity.

Zuckerberg however kinda forced his philosophy of "privacy is an outdated concept" on us, and a lot of younger people without sufficient internet or life experience fell into that trap. This guy actually does some harm. And no, I don't think it's fair to blame a bunch of kids for being naive.