To be fair, Sanghee worked hard for it. It's the result of Sanghee being different and smarter. It's also not an excuse for their attitude. Instead of uniting together, they built a huge wall between one another and attacked those who are weaker than them. Most of the older Princesses are arrogant, too.
It’s the result of her being different not smarter, she is an adult. It’s not but they are still children and can’t understand how can she be that different from themselves and they were born in a different world which they don’t have a value and they accepted it and they expect sanghee to be like them too. Imo older princesses are arrogant not smaller ones

I pity other princesses… they probably feel unfair about sanghee’s situation :((