So are you believing that the rock world was still somehow a physical evelyn? Cause I see that as a major flaw in your reasoning.

And im surprised no one here is talking about the obvious depression and shame that led Joy to feeling so lost. I felt the whole movie was her searching for a universe that could explain why she felt worthless because if things outside of her control. Then she seeks what everyone does, comforting. Whether in the acceptance of a loved one, or in leaving it all behind, they just took it to a very extreme sci-fi level. It wasnt just suicide, it was ending all of her, everywhere, all at once. The pain if life and the reality that it will be there no matter what choices she makes, make her angry and want to bring the attention of others to the answer she found. Which is that the universe is fucked and not worth existing in. She finally finder her mother who understands and fights to change, but the pain is so deep that she thinks it would be better of her mother joined her in death. Why wouldnt someone want to free their entire existence from pain? And once you've settled that suicide is freedom from pain, its pretty difficult to win you back.

Maybe I've just known too many people who have commit suicide because if feeling there was nothing for them in life, no joy, no hope, no comfort. The idea of exploring an endless number of possible different lives and still finding the same end result would only further that need to just end it.