Kat, I can't quote any research, so this must be taken as my personal opinion and possibly incorrect, but I have a sneaking suspicion that many people who want to ascribe the "white supremicist" style of behaviour to fear of the unkown do so because they do not want to believe or contemplate the alternatives.
These alternatives of course range from the idea that some people love exercising power and for those unable to do it another way physical violence is a good option; to the idea that there is a provable gentic difference between races which justifes group A as defining themselves as superior.
the latter is of course anathema to "liberal" organisations, but unfortuantely for them, there are distinct racial "tags" at the genetic level, and since any so called test of behavioural difference only measures what you want, it is easy to define one which demonstrates your viewpoint. For example see S. J. Gould's "The mismeasure of man".
Personally I don't think there is any one reason which can be applied generically. Unlike Rick I don't think education is ever too late, but I do agree with him that it is not enough. Which brings us back to the same dilemma as the situation on Kosovo. How do you restrict the activities of these goons without causing greater harm to the general population?