Humans are apathetic creatures by nature.  We don't bother to take action unless we're threatened.  Back when we were wearing pelts and living in caves, a "threat" was a life or death situation â€" but our evolutionary roots are still there today.  Except instead of saving our young children from a saber-tooth tiger, we're fending off sales messages that threaten to quickly snatch our cash right out of our wallets.