Chen Ran made this choice not to sacrifice herself or save others, but simply because she, like those children driven to jump off buildings by their parents, found no way out and chose to commit suicide.
Sending Fu Chen back to the real world was merely a 'byproduct' of her decision.
Of course, Chen Ran definitely went through some simple thoughts in making her choice.
Although initially, Chen Ran was wary of Fu Chen and didn't accept his goodwill, afterwards, Fu Chen's actions in helping all players share the punishment and encouraging everyone with his positive and optimistic attitude somewhat affected Chen Ran.
Perhaps she felt that someone like Fu Chen shouldn't stay in the cruel New World, or maybe she was simply envious of Fu Chen's personality and family relationships, having a mindset of "live well for me."
