I'm thinking, in this thread, more of a "Why do I help people" versus why am I good in general.
I don't expect a reward, they never come. No karma especially - I've the worst luck a person could have really.
I certainly wasn't raised to be a good person. My dad's advice was "Don't get caught." with my mothers "Do as I say, not as I do... (but also I remember I reverse psychology everything I say.)"
I think it was more of a frustration with the entire population - humanity as a whole. None of them really lived up to the standards other people had of each other. Gratitude free, ungracious, self-helping and constantly complaining that everyone else was just like them.
At some point in my life, I realized I could only change myself and just decided upon myself to journey into being a 'good person'. Baby-steps, but after many years, I've collected many good qualities.
But no friends. Being exploited for being a good person is almost as bad as being a good person. Karma does not exist. I've never been rewarded for being a good person. Not in a spiritual sense and especially not in a material sense. But especially not in a monetary sense.
I half use the bible as a morale compass with the "thou shalt not's" as best as I can.
(I'm not one of those obsessed devout worshipers who uses the bible as a history book!)