I really do believe in a sort of karma. Not exactly "an eye for an eye" kind of justice for every positive and negative action, but the kind of accumulation over a long period of time that tends to give back to you what you have put out there for others. Sure, some people seem to give good and get bad, while others seem to escape their bad deeds FOR A WHILE. Maybe even for a long time. But I just have this feeling, gathered from years of observation, that statistically, people tend to behave mostly positive or mostly negative MOST of the time (with exceptions, of course). And that over time, other mostly negative or positive people are drawn to their own type of people, and thus spread and accentuate "good or bad deeds" among themselves.
Or maybe it is just the Universe (or whatever you believe in) trying to keep some sort of balance. Whatever the cause, it is often in your own self interest to generally treat others as you would like to be treated. And the younger you start, the more likely positive actions and thoughts will be with you for your whole life. It is much more difficult to change later in life.
Please do the right thing.