They still exist for the same reason the Black Panthers still exist and the same reason La Razza exists. I find it amusing when minorities want to bring up the klan, but refuse to point the finger at their own racist groups.
The klan is nothing more than a crutch all (minorities) lean on to talk trash about the white race, it is truly the only thing left that the white race has that you can truly point a finger at and say, "That’s wrong, and it should be abolished," and "see, white people are racist," but this is America first and foremost...Which means that the klan can exist, the same way the black panthers can exist, but most minorities are to simple minded to realize this, even though minorities and others proclaim that the clan is the one that is simple minded.
I believe racism is wrong, by no means am I trying to say that the klan is a good thing, but you need to realize that there are racist groups in every race. Your question should be, why does Racism still exist?? Not singling out one racist group out of one ethnicity.