>>6499575Because that's only reasonable if you believe you can't have any effect on people around you. Social interaction doesn't start and end between two people, it has a ripple effect. You are nice to someone in your average day, hence that person will have his mood improved. It is reasonable to assume that happier people are statistically more likely to be nice to other people. Therefore if you improve the mood of one person, you very slightly improve the odds of other nice things happening around you. It's a numbers game
