That's... not what this means.
The "enlightened" in "enlightened self-interest" means knowing that doing underhanded things to serve one's own self-interest doesn't actually work. When you hurt someone, their opinion of you will go down and that makes it harder to operate in the future, no matter how insignificant you think they are. The more underhanded you are, the more lying and cover-up you have to do, and even just on a practical level that's much more difficult than just being nice in the first place - and on top of that, the psychological toll it takes will kill you (see Macbeth).
That's... not what this means. The "enlightened" in "enlightened self-interest" means knowing that doing underhanded things to serve one's own self-interest doesn't actually work. When you hurt someone, their opinion of you will go down and that makes it harder to operate in the future, no matter how insignificant you think they are. The more underhanded you are, the more lying and cover-up you have to do, and even just on a practical level that's much more difficult than just being nice in the first place - and on top of that, the psychological toll it takes will kill you (see Macbeth).