When/why/how did 4chan get so racist?

I mean 4chan being full of fucking idiots isn't anything new, but jeebus.

It's like this. I don't hate black people for their color. I really don't. I don't hate them for their race, nationality or whatever. I hate how most blacks act.

When i see a black, i just think they are most likely obnoxious, not because they're black, but because most blacks i met are. I may be slightly prejudiced, but if a black talks to me and seems intelligent, i'll treat him just like i'd treat a white or whatever.