I didn't want to say something to "gamergate" since I'm not even a real gamer, just a casual. But I find it simply horrible what people are able to do, and death threats and harassment should be punished with jail or a very substantial money fine. This has nothing to do with "free speech," your freedom ends where the freedom of the other begins.
That said I'd like to point you to a very interesting blog post by Seriouspony. It talks about a phenomena called "the kool-aid point". It describes that in the beginning people who don't like you or your ideas ignore you and as soon as you get attention they get nasty, because they think that you don't deserve this and because they want to get some kind of revenge.
I can totally confirm that theory. I made similar experiences (although not that hard, I never got death treats but I've been doxed and harassed).
This is serious, people. It's not less serious because you do it on the internet. It is even more serious, because people can still read it after years.