She has always come off as extremely spoiled, lazy, and entitled. Back when they had their reality show on MTV, she was very bratty.
Her priority is her appearance and being thin. She was a little chubby when she was younger. Sharon struggled with her weight all of her life. I’m guessing there was an environment of body shame and growing up with that has affected her.
Being skinny is obviously more important to her, and even more attractive/prestigious than being fit and strong. Enough to overlook the potential hazards of using weight loss drugs. Hopefully the weight loss drugs won’t mess her up the way they have her mother.