There are "observable" instances of something from nothing continuously happenning in the universe, known as quantum fluctuations.

Particles and anti-part particles form spontaneously and then combine and become nothing again.

So if something can come from nothing on that scale then why not on a larger one?

I'm not the one you should be directing this question at but maybe reading one of the many books on the subject may direct you to someone better equppied to answer your question.