Miserable People

I once asked my old man why a certain customer was being so mean.
He smiled, patted me on the head. "Son, there's two kinds of people in the world, happy people and miserable people. Happy people are always happy no matter what, miserable people are always miserable. And their mission in life is to make you miserable. Run from those people. Cause...no matter how hard you try you can't make miserable people happy."

Then he smiled and grabbed my arm, pulled me close. "But we need miserable people."
"Why do we need miserable people," I asked.
"Cause miserable people make the rest of us look good."