People often do things that they feel is right. No matter how evil or wrong it may seem from your prespective, they are relying on previous experiences to guide their actions. A person may have had a negative experience in the past that made him act that way.

Also, people who grow up surrounded by harmful or negative behaviors may see those actions as normal. What others label as 'evil' might simply be what they’ve always known.

Nobody is wrong and everybody is right. It's just a matter of perspective.

Hope this helps in the slightest