This is a thought I had since a very young age.
It seems that the only way for existence to appear out of nothing, or at least out of minimal necessity, is to be the single branch, out of all the possibilities/rearrangements, that never gets destroyed.
All possibilities exist, e.g., there is a possibility/a world, where everything explodes in the next second, but it never materializes because everything is ending/will eventually end at some point. The everyday concept of time might not properly apply here; regular tenses of everyday verbs might not make sense.
This might be relevant to the many-worlds interpretation of quantum mechanics.
Still, it doesn’t account for the existence of the possibilities themselves. Why should the possibilities themselves exist at all?