Why are suicidal people eager to take innocent people with them?

When I was growing up we heard of people committing suicide. Today there seems to be a growing trend to kill your family before you off yourself or even kill a large number of innocent people on their way to hell. I know no one in Fluther can actually know why, but I would be interested in hearing your theories. This is the latest attempt at mass murder aboard a flight by an off-duty pilot