There is more to the story of childhood diet than simple narratives of cheap nutrition, though that certainly plays a massive role. Consider, for instance, eating disorders, including some which may be mistaken for playing into aforementioned narrative, such as binge eating (a common symptom among eating disorders in general and often co-morbid with eating comforting but "bad" food) and picky eating (such as ARFID, also correlated with eating comforting but "bad" food). In neither situation is the consumption of the "bad" food the cause or most even the most harmful symptom.