I won't label virtuous behavior as stupid. I've been known to point out other's mistakes when I would have gained a fair amount by keeping mum.

OTOH, the airlines have the upper hand and are constantly revising the rules. PAX have little say and practically no room to negotiate. Though preferring principled living to "situational ethics" I admit that I'd think about it a bit before pointing out a mistake of theirs that I stand to benefit from. IMHO most of the airlines are not all reluctant to cash in on PAX mistakes. I'd be surprised if this wasn't part of the calculus behind non-refundable fares etc.