Implicit in the question is the possibility that there could have been nothing, and that's wholly unsupported by observation; even the vacuum is full of virtual particles.

The still-confusing part of "Why is there something rather than nothing?" isn't "Why is there stuff within this universe rather than no stuff within it?", it's "Why are there these particular laws of physics in the first place?". That may yet (probably will) turn out to be confused/meaningless, but nobody has satisfactorily shown how it's meaningless. I still very strongly suspect that Tegmark is on the right track, but the measure-of-experience problem currently prevents it from counting as a satisfactory dissolution of the problem.