Barbara Oakley examines extreme altruism:
Pathological altruism is associated with disorders and conditions such as anorexia, the amorphous traits of codependency, animal hoarding, depression, excessive and misplaced guilt, and self-righteousness. It is also seen in suicide bombing—the one common trait of suicide bombers is their sense of altruism for those who share their ideology.
Pathologies of altruism can even underlie genocide. A Rwandan Hutu, for example, didn’t wake up in the morning and think “Gee, I’m feeling totally evil today—I’m going to go out and kill Tutsis.” No—instead, he thought—“I’ve got to protect my family and people against those cockroaches, the Tutsis.” In other words, it was feelings of altruism, as well as hatred, that impelled many Hutus to kill.
The Dish 