I'm not an expert by any means.
But I think that the only way we can exist is because 'something' MUST ALWAYS come from nothing. That is something related to the laws of Quantum Mechanics.
My understanding is that, the question in the OP is based on this premise of 'Classical Physics'. In Classical Physics we assume that for something to happen we must first have an instant of causality. So cause equals effect.
However for things at the smallest scale, which we call the 'quantum' scale we find that a different set of rules apply. And we believe that our universe came out of this quantum scale.
These Quantum Mechanical rules are EXTREMELY different from those of Classical Physics. Cause does not necessarily have to precede effect.
Honestly I don't know much about this stuff, but based on what we think we know; the universe as we know can have come out of nothing. In fact according to some scientists, it is necessary for that to happen (for reasons I don't know).
The key thing here is that the question in the OP is based on this idea of cause and effect. Quantum Mechanics does not operate on that principle, there are a completely different set of rules that do a pretty good job of explaining the formation of the universe up to this point in time. The Higgs Boson (allegedly) discovery reinforces the standard model of Particle Physics, however this is proving to be a problem now, since we need more data for the standard model to work.
