The point of the Movie.
Many gay males like "difficult women" who are "train wrecks" and some examples of gay female icons are Marilyn Monroe and Elizabeth Taylor. They are flighty impossible to please females who are castrating to males. They went through men fast, were divas, addicts, and so forth.
In older psychology it was thought that these kind of women secretly hate men and if they have a male child he might turn out homosexual due to her man hating. That may or may not be true, but it is true that many male homosexuals idolize diva types. So, there is a reason, but it may not be that one.
I am just reporting facts.
Anyway, Holly Golightly is such a woman as I talked about above. She was sexually molested as a kid, and became a sociopathic prostitute. However, she is pretty and so you wouldn't think of that by looking at her. She also has Borderline Personality Disorder qualities where she plays people to disappoint them later. But, mostly she is a sociopath that uses her charm and looks to trick men into giving her money, so she's not an "honest prostitute" charging a certain amount.
In the movie, she is shown to be a hurt vulnerable person, due to the hillbilly upbringing and molestation. So, the lead male is an awesome guy and he loves her and understands. He doesn't want her living this cynical life. He works hard to show his love and she accepts it in the end over marrying someone she doesn't love for money.
In the novel, the story is about a person who knows her and learns her weird story. So, it's about a "creature" like a vampire, telling you her story. That's the point of the novel.
I have had the fortune/misfortune of knowing women like this. They are sociopaths and aren't going to fall in love with anyone. They will string you along and fuck you up, if you don't have cash to fuel their parasitic life.