Another argument derives from Aristotle's Ethics. He asked how any thinking person could be happy.  No matter your current state of affairs and reasons for felicity, you must always be aware that all could change tomorrow.   You could be struck mute and paralyzed. See your fortune lost to theft or opportunistic legal actions, see your sons killed and your wife and daughters raped and be powerless to prevent or avenge these events.  Knowing this, how can anyone truly be happy?  My father used to say: "Only fools are happy."

Think this surely can no longer be the case?  Consider the latter years of Joe Kennedy.  Consider John Ramsey, his wife Patsy and their daughter, Jon Benet.  The only possible defense against such calamities is a strong and caring community and a just society.  We are far from it.  Your friends can deny that this will happen to them and may well be right, but perhaps these considerations will at least disturb their sleep.

Have any of these things  

If sanity be culturally normative, then by the norms of this culture I claim insanity.