It Just Takes One

So life has been pretty rough on my family lately. I mean, our car breaks down every other week, we never have much money in the house, and just a few days ago our sewer line broke. It really sucks. But I was doing fine. Until one person in the family decided to go haywire. The whole week (which, for your information, started out GREAT for me) has been awful. I've learned this week that it only takes one person to bring everyone down. It only takes ONE person to make everyone else miserable. It only takes ONE ill-considered word to turn someone's life upside-down. And it not only affects the sender and receiver of the action, but everyone around them. Why do people choose this path, which can only lead to misery and unhappiness for large quantities of people?
It only takes one smile, one wave, one simple gesture of kindness or caring to make someone's day better. It only takes one kindly sentence to change someone's life.  So why can't more people show THIS side of themselves? It would make the world a much happier place. I really just don't understand it.
If you see someone who looks upset or lonely, don't just sit back and watch them. Go to them. Be kind to them. Who knows. Maybe you just saved their life.