People have been asking this question, since the dawn of humanity no doubt. As of today, the question still remains unanswered, and I suppose we may never have the answer. I strongly doubt there is an answer.
In fact, I think the question can be phrased into a statement: our existence is just too be good to be true. I think the former statement gets to the heart of what people usually mean when they are asking why the universe exists. Is the universe too good to be true? Maybe. Maybe not.
Let’s assume the probability of the universe is very, very low. With this assumption, many declare a deity has to be involved in the universe. However, consider this: the universe only had to happen once. If there are multiple universes, just like our own, I admit that would be suspicious.
To clarify, let’s say we’re gambling. I bet on a number on six sided die. I earn money every time the number I chose comes up, and I lose money every time it lands on another number. The chance of my number coming up is 16.7%. (This is low; although, conceivably much higher than the chances of a universe). We roll the die. My number shows up, but I’m not surprised. The chances weren’t good, but it had to land on one number, and it is just as likely that my number will come up as opposed to any other number. Now, if my number came up over and over again, you might suspect the die is unfair, and depending on how many times my number came up, you might be right.
I don’t have the answer to why there is something rather than nothing. Perhaps, it has an answer, but I’m not convinced by fine-tuning arguments at this time.