This is not funny
Do you think the man who drove the plane into the building was sane at that time? The economy is bad and this guy was having money problems. He was stressed. Stress tends to cause people to get mad and when there is an unmanageable amount of stress, people can go insane. This man was likely slightly autistic and it probably never affected him until he broke under pressure so it is likely not diagnosed.
So why can't temporary insanity be funny? Temporary insanity is not fun and that is why. Are you afraid to work too hard because you might go insane and kill somebody? Sometimes I am because I have gone insane. I threw something at somebody who was asking me why I was crying. I got closer to killing somebody than I have ever wanted to that day. If you are insane, you can exert no logic into your actions; you have no control. Few people have had to experience this, but if they have, they would agree with me because it is a traumatic experience.
I am insulted.