In Ender's Game Why does Graff want to manipulate the games?

In "Ender's Game," Colonel Graff manipulates the games to push Ender Wiggin beyond his limits, believing that extreme pressure will cultivate his exceptional strategic abilities. By isolating Ender from his peers and subjecting him to intense challenges, Graff aims to create a leader capable of defeating the alien threat. This manipulation serves Graff's belief that only through adversity can Ender realize his full potential and emerge as the savior humanity needs. Ultimately, Graff's actions reflect his commitment to winning the war, even at the cost of Ender's emotional well-being.