There are innumerable reasons to want to kill self and every one of them is a measure of desperation. There is only one reason to want to kill someone else - hate. Hating enough to act is most likely the result of a perceived injustice. The validity of the injustice cannot be challenged because contrary to common belief justice is subjective.
Terrorists who want to destroy American culture by violence are as wrong as the American/European axis of elitism that works to maintain a white superiority complex about the quality of being Human.