I was at the birth of what has turned into the current "Anonymous" and it's sickening. There was a short story by William Gibson in Burning Crome that I think describes these "people"
This guy has most of it right.
TL; DR: 4chan veteran explains it for the newbies in the hope that it will at least partially help to improve the site.
4chan (4channel)is an image bard based on, and inspired by, 2channel (2chan.net) which is a japanese image board. It is the largest english speaking image board of its type. It is a website designed for adults only. The culture of 4chan is a deeply complicated one. It is japanese themed and inspired. The boards were originally organised by letter, a b c and so on. /b/ was and remains the "random" board, which is by far the most visited board on the site, receiving as it does over 100,000 posts a day. However, it is nothing remotely like or related to gaia. It really is an adult web site. The long running joke that has developed over the past 3 or so years is that everybody on the website, (well, on /b/ anyway) whislt ADULTS, and reasonably intelligent ones at that, engage in moronic activities verging on the utterly stupid. The joke being that everyone acts like the same retarded individual. WHILST KNOWING THAT THEY ARE NOT. The joke is in the delivery.
The humour was fairly unique, and rediculously complex and almost impossible to follow as a newbie. The problem that has blighted 4chan in recent years (and which really started to kick in about 2 or so years ago) is that newcomers to the site, usually heading to /b/ to see what the fuss is all about, see the retardedness of people acting like 14 year olds, and then start thinking that indeed, the website is a place for 14 years olds to hang out and be retarded. This in turn lead to masses of underage users flooding the site. Recent media attention makes this problem increase. Eventually, so many 14 year olds end up browsing the site that the original adult userbase has been overshadowed by the masses of underage people who have now turned the joke inside out, and the site has now literally become a place for 14 year olds to be retarded.
There are several problems with this. The first is that all the old populace of 4chan start whining about this very fact. The second is that the quality of posting completely degrades. The old rules were that you would have to lurk for ages before posting. And you actually would, because the in-jokes were so obscure and closely knit that lurking was the only way you had of knowing what the hell was going on. People now don't bother, and so many new users means that the original point of the board (an extention of a something awful sub forum celebrating a retarded sense of humour crossed with a love for japanese animation) has been wiped clean.
This is a direct result of the board acheiving widespread popularity and new users from sites like this. So now, rather than massive photoshop contests (similar to photoshop friday on something awful) or well written stories, either humerous, or completely obscene, written by adults, the board is flooded with people posting pictures of themselves, reposting old, long dead memes (memetics; the idea of something catching on to the popular masses, think the stuipid "whasssup" budweiser adverts... idiots shouting it at their freinds and so on) that are no longer funny, people taking the idea of anonymous/legion seriously (protip: it's a joke) people reposting threads such as "you raff you ruse" without sometimes even knowing what that means, and generally forgetting that 4chan is an IMAGEBOARD and that posts should be all about interesting/freaky/funny/downright disturbing photo's, drawings and photoshops.
I digress. The next president should require metal detectors for all Colleges/Universities, and high schools.