Where it does actual damage

Not in feeling bad for an evening. In changing decisions. Someone drops a subject they were doing fine in because two people around them found it easier. Someone stops applying because a classmate got an offer first, reading one data point as a verdict on the whole market. The cost is not the discomfort, it is the choice that follows it.

The tell is when a comparison changes a plan you made for good reasons on better information. The version of you who chose the subject knew why. The version reacting to a classmate’s result at eleven at night knows less, not more — and is the one making the decision.