Actually, it's more along the lines of a stupid question.Why is any of the shinobis who are still fighting alive? You are obviously a troll or hater so enjoy the attention while it last.
She's an important Medical nin in the war. Partly Narutos motivation ( The whole Sasuke thing got so intense because Naruto made a promise to Sakura ) Important Character in general.
Before anyone writes '' She's useless '' She's actually one of the most impotant Ninja's Duo to her Medical skills. If you pay attention you see that she's more skilled than many other Medical nins. She was declared learder for the hospital during the pain invasion. There where severel other Medics but she got the role of leader. She also took part in the killing of Sasori. That all leads to her being incredibly strong.
NOTE - I really hate her but i'm not blind. She's a strong ninja.