Why? Breakfast at Tiffany’s is a remarkable book. If you’ve only seen the movie you might get the wrong impression of the book. I had to turn the movie off after just a few minutes.
It embellishes by establishing a romantic relationship between Holly Golightly and the narrator, and then also makes the narrator himself into essentially a prostitute, as Holly was also. Moon River is also a major addition, as is Holly's decision to remain in New York at the conclusion.
They even kept the cat in the plot, for most of the same story.
https://en.m.wikipedia.org/wiki/Breakfast_at_Tiffany's_(film...
Or how about Gone with the Wind itself: The novel and book deal with many universal themes of families, love and human ties being destroyed and deformed by terrible circumstances outside of individual control. Many, many victims of political and social tragedy from any time in history right to the present can easily identify with that central concept without being completely blinded into flippant, fashionable woke dismissal by focusing only on the type of society portrayed in the book and film. The movie's central emotional drama is nearly universal to human history. This is why it was so enormously popular, and its central emotional concept still is today.
1. https://en.wikipedia.org/wiki/Gone_with_the_Wind_(film)#Anal... 2. https://www.cnn.com/2020/06/12/opinions/gone-with-the-wind-i...