My only experience on 4chan was due to a Google Alert notifying me that I was the subject of a thread on /d/. That thread was the highest density collection of insults about me that I'd ever seen on the net, and sadly, I'm not yet thick-skinned enough to entirely ignore the "comments on the internet."
When I see things like that, or comments on youtube videos of my talks, I sometimes think "maybe I should retreat and make myself not such a visible target." But I stay because I feel like I'm meant to be a role model for my gender, and people seem to like to hear the things I say.
Or at least, I stay for now.
I get the impression that communities like this feel that people put themselves out there purely for their own benefit, and therefore they have the right to attack them, because they are asking for it. I think many of us never asked for it, but given the pros/cons, we stick with it. There are definitely cons, though.
I don't see how to prevent anonymous communities from lambasting public figures, and don't think they should necessarily be prevented. But it sure would be nice if they realized that everyone's a person, and nobody likes to wake up to find they've arbitrarily been chosen as the subject of taunts for the day.