"why is there something instead of nothing"
What an amazing question. I really used to ponder over it. The great presocratic Parminedes answers it. There can be no such thing as nothingness. There's only beingness. Once we realize 'why something exists instead of something' .next step is to analyze is the nature of nothingness and existence. Nothingness cannot be. Because what is not IS . That is a contradiction. Neither can nothingness can be a predicate. Unicorn don't exist. Is a contradiction. Because even by uttering the word 'unicorn' we ascribe a certain ontological status to it .even if it is in our minds. It has certain properties . A certain form. So when we say unicorns don't exist.So logically what we are saying is. "a unicorn(a horse with wings) is not a horse with wings." Because it is not. Whole Eleatic philosophy is based on rejection of nothingness. Which results in a logical necessity for things to just exist.