->''"When they realized they were in the desert, they built a religion to worship thirstiness."''
Sour Grapes Tropes are tropes that exist to convince the viewer that not only is it unlikely that their dreams and fantasies will come true, but it's probably better if they ''don't''. This is done by showing how a character is made miserable when getting their wishes fulfilled.
Stories that don't do this are WishFulfillment fantasies. NotThatTheresAnythingWrongWithThat. Fiction has been providing wish fulfillment for centuries. Contemporary fiction, though, often comes off as somehow ''obliged'' to show the downside of a desire. Not doing so might be seen as "juvenile." Ironically, SourGrapesTropes tend to [[NotSoDifferent indulge in their own backhanded brand of]] WishFulfillment; these tropes are often used to assuage [[TallPoppySyndrome an audience's discomfort]] and [[GreenEyedMonster jealousy]] at seeing a more ambitious or intelligent or lucky character at succeeding in a way that the viewers can't by showing the 'bad' side of their success. See [[FriedrichNietzsche Nietzsche's remarks on ''slave morality'']] for the intellectual impulse behind many of the usages of these tropes.
These tropes can also be used to make a FamilyUnfriendlyAesop if one of the things the Sour Grapes trope is grousing about is something the viewer can genuinely attain. It can encourage them to stay in their bad situation rather than [[DareToBeBadass doing something about it]].
Note that the original fable"The Fox and the Grapes" is not about disparaging a thing you can't get. The fox was disgusted with himself for wasting time and effort trying to reach a bunch of grapes that were sour, meaning unripe.