One thing many juvenile questioners don’t understand is that getting answers isn’t some kind of philosophical entitlement program where all you have to do is show up and stick out your hand. If you are going to ask questions and expect rational answers, then be prepared to answer why your question makes any sense.
Regarding the question “Why is there Something rather than Nothing?”, pay special attention to the term “Why”. Anyone demanding to know “Why” must be able to answer: What sort of answer counts as an answer?
Whenever we ask why any element of physical reality is what it is, in every case we are presupposing cause and effect, i.e. some prior element(s) from which the given element springs. In other words, to ask “Why” some part of physical reality is what it is is to presuppose that physical reality exists.
So, to ask “Why does existence exist?” without specifying some special new meaning of “Why” is to beg the question – your question presupposes as the only possible form of reply that existence exists because it exists. At best, you are asking how some prior state of existence led to a later state, but then this becomes an ordinary question of physics framed in a philosophically obtuse way; it is not some profound philosophical question.
Barring some genius that wants to specify how and why his “Why” makes sense, we can safely answer the question: It’s a meaningless question. If the questioner still isn’t satisfied, we can only refer him to a psychologist.
Remarkably, physicist Lawrence Krauss wrote an entire book that orbits this philosophical silliness, called A Universe from Nothing. Very predictably, he doesn’t answer the question except by positing a special state of Something that preceded the Something we’re more familiar with.