Is karate evil?
Witchcraft (like martial arts) is a learned skill. It can be used to protect and heal, or it can be used to damage and destroy.
Witchcraft is neutral. Practitioners (witches) are said to practice along the left hand path (centered around the self, personal needs and wants, with little regard for the effect upon others) or the right hand path (centered around the community and caring for it, with full regard for the needs and wants of others.
In truth, all witches practice a little bit of both. Witches are human beings with a skill. Like any human being, they are not always truly selfless, nor are they always truly selfish.