The selfish motive behind philanthropy

I don't know if the selfish justification for so-called good actions (like love thy enemy) is such a good idea. Maybe it will motivate me - that goodness is economically and logically sound in the long run. Lets say we run a school for the poor providing free education to them - long term we will have the goodwill of these poor people and their parents and community and we will get politically powerful in the long run. If that motivates me to open a school for poor is that good ?