Why does the KKK hate everyone not like themselves?

It's called xenophobia, which, as the 'phobia' suffix suggests, is an irrational fear and hatred of something or someone. In the case of the KKK it's fear and hatred of strangers, foreigners, or - as you say - those not like themselves.

As with all phobia sufferers, xenophobics are easily frightened by anything relating to their phobia. Many organizations similar to the KKK are led by people who aren't particularly xenophobic at all, but are greedy for power and wealth; this is sometimes achieved by gathering a following which is easily led.

An added inducement for those attracted to the KKK is the 'secret society' aspect, which gives many a feeling of belonging to something special, together with the feeling of superiority which all secret organizations induce in their followers. This appeals hugely to the basic feelings of inferiority which those such as xenophobics work so hard to conceal.

One only has to read some of the claims made by such organizations to see they are carefully-Worded in order to attract exactly the type of people who truly want to believe such claims and won't question too closely their veracity, or ask for hard facts and real proof.

You'll find doubters and questioners and those who expect logic and verifiable truth in the information they are given are not welcome in organizations such as the KKK.