Because there was no big bang. The universe slowly goes to the "black side" through black holes, and when it's finished, it goes to the "white side" in a kind of big bang, but no so violent. And the cycle repeats.
It might be unrealistic to expect any proffered answer to come with a reputable citation.
One could argue that metaphores are a step to move the science back toward reality and "complete the circle".
This doesn't seem to describe the previous comment. It's not just invented, and not emotionally compelling. It's just a fun idea.
> You can't skip straight to the metaphor! Where are your numbers?
I have a story about ants on a rubber sheet for you.
Bingo. Whatever evidence is claimed to exist is only ever indirect. We cannot recreate the big bang, claiming it happened is worse than claiming it didn't happen.
I don't think your black hole points are correct but it's fun to consider.