She's a teenager. Her personality is not fully formed yet, and she's under a lot of hormonal stress, anyway. It's likely she'll be a lot better adjusted as an adult.
granted, personality is still malleable, especially traits like conscientiousness and openness. But she's what, 17/18 in the manga? at that point core identity is already impeccably solid, and only life-changing or strong environmental stimulus could really have any effect on remolding her character. Considering how spoilt and silver-spooned she is, that's highly unlikely to happen. not to mention, her character is so far defunct that you could write an award-winning thesis on her Machiavellian disposition.
trying to fix that now is like trying to put out a house fire with a squirt gun.
That being said, her character is largely just comedic relief to sand down the sharp edges of tension in other-wise solemn scenes. It's highly effective in mangas where comedy shouldn't affect the credibility and 'flavour' of the romance. Overly-dramatic and obnoxious humor often plagues the narrative and starts to corrode the authenticity of the world and it's characters. In order to keep that separate from your main cast and their interactions, you'll need a 'sponge' character--someone who can be your scapegoat for all the theatrical excessiveness. In consequence, these characters tend to become marmite... one side loves them, whilst the other hates them.
If we take things at face-value, then Fujiwara will likely never change. She's a family that spoils her, and also shares her self-serving habits. She has friends that simply accept her personality (like when Kaguya said that she just learnt to accept that Fujiwara is unreliable). She has intelligence and strength that allow her to enter any college she wants, and the brains to pursue her career without the cold-shower-shock of set-backs. Not to mention that she largely seems to never learn from her mistakes, and often repeats them to the same conclusion. The future career she wants to enter is also littered with like-minded individuals that share her maladaptive traits and poor character. All that combined, and considering she's unchanged even after high-school, she's practically entrenched inside a social sphere of mutual enabling.
It's highly likely if not inevitable, that her character will stay the same.
That all being said, she's literally just a comic book character... and it's 4am, and I'm most definitely reading too far into what is effectively just a stylistic choice on the author's behalf. But most importantly... this is all just cogitation and conjecture... an
opinion if you will. we're all welcome to come to our own conclusions.
