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.
This isn't likely since the geometry as we've attempted to model of the inside of a blackhole wouldn't be so flat. There's a PBS Spacetime episode covering this idea and they explain how it's not possible and if it was possible how it might be so. In any case, the answer is probably no.
I think you rather badly misunderstand what physics is. It's not a field where you try to convince people of some kind of emotionally compelling origin story you just invented. It's a field where you measure a bunch of things, relate the numbers with some sort of equation, and (optionally!) describe the equation with some sort of layman-friendly metaphor, to build intuition. You can't skip straight to the metaphor! Where are your numbers? On what basis do you claim this radical departure from established physics? Why should we listen to you?
And I think you forgot we're just commenting an article on hacker news, not publishing to a physics journal :) By skipping to the metaphor I'm doing a small inception in your minds, you physicists out there. Now this idea will never leave you :)
And are we sure it doesn't predict cosmic strings just as much as the big bang model does? Both involve the universe being very hot and dense in the past and then getting rapidly cooler. That's the part that makes physicists expect cosmic strings, not the question of where the hot-dense state came from in the first place.
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.