There are many sayings and idioms related to the general idea of “karma”: that good things happen to good people, and vice versa:
It is a comforting notion. Because it’s so comforting, people seem to genuinely believe it is true. But it is demonstrably untrue. It is a fallacy: the just-world fallacy.
An easy example: babies and young children are too young to have virtually any ability to do anything, good or bad. We would expect in a just world, then, that nothing terrible should ever befall them. And yet they get sick, or are subject to war and devastation, or are abused by their caretakers, or are abandoned, or die.
It’s bad enough that bad things happen to those who’ve done nothing wrong. But it’s even worse that people who believe in karma thus come to the conclusion that if bad things are happening to you, it’s because you deserve it.
This breeds an attitude of mistrust, fear, and derision towards those who are less privileged than others, even though they need society’s support the most. And in turn, it contributes to idolization of the rich and powerful, even though they often gain and entrench their power by exploiting the weak, skirting or outright flouting the rules, and privatizing gains while socializing losses.