(My Input)

When you delete Monika at the start of the game you get the Sayori becomes president ending.

(Their input)

Sayori freaks out and it cuts to the image of her hanging body. Before, I figured the sudden knowledge of her newfound powers made her go mad, but now it occurs to me that the memories of her time in the other reality drove her to suicide in that instance. So when she becomes the 'president' in the game proper, knowing about her manipulated death would be par for the course on top of everything else. She could more easily accept the way things were because to her, it was all the same, at least she could change things for the better now. Jesus the more you think about it the more effed up it gets.