'..it is wiser to teach such people modesty, and
how to be kind to others..'.

One cannot 'teach' empathy to individuals with antisocial or other personality disorders and/or psychopathic facets...and there are more of those leading work places and communities than most realize. Some psychologists believe a psychopath can be 'healed', but all relevant history and data reveal such believe to be erroneous.

I do opine that no one should hold grudges, but only because holding a grudge harms the individual intent on holding a grudge.

In conclusion, when I noted '/sarcasm' regarding vengeance I was being both playful and...dishonest...because most anyone do not take things written in comments seriously.

I have zero empathy for individuals who believe it is their purpose to make others suffer, whom delight in observing the suffering of others, whom believe the world must lay at their feet at the cost of others.

I delight in exacting vengeance on such individuals--the alternative is to develop and 'hold' a grudge, which is self-destructive.

I advise people do likewise--exact revenge, calculated, methodically, carefully, to ensure one 'comes out on top'--it is liberating...exhilarating. And you may discover new things about yourself.