I don't know the technical/methematical explanation for this, or if one is really needed (though it seems like a valid question to pose), but it is noteworthy that black holes and the big bang are the original "singularity", and that there are several related theories in which they are directly related, notably Big Bounce[1] and my favorite (which I learned of from Lee Smolin's amazing Life of The Cosmos[3]) Cosmological Natural Selection[2]. There's also a variant of Cosmological Natural Selectionm CNS-I[4], but that one possibles borders on religious, though it's possible it could be falsifiable/supportable some day by modeling.
I suppose it's even somewhat plausible that the answer to your question, in combinations with the other theories, are "all true", and that for various reasons or models the first N big bangs did result in immediate/fast collapse back to another big crunch/black hole, and that each subsequent crunch/black hole created another universe, until there was a universe that survived long enough to create several black holes, and so on and so on...
I suppose it's even somewhat plausible that the answer to your question, in combinations with the other theories, are "all true", and that for various reasons or models the first N big bangs did result in immediate/fast collapse back to another big crunch/black hole, and that each subsequent crunch/black hole created another universe, until there was a universe that survived long enough to create several black holes, and so on and so on...
[1]https://en.wikipedia.org/wiki/Big_Bounce [2]http://evodevouniverse.com/wiki/Cosmological_natural_selecti... [3]https://www.amazon.com/Life-Cosmos-Lee-Smolin-ebook/dp/B004T... [4]http://evodevouniverse.com/wiki/Cosmological_natural_selecti...