If you read between the lines, I know this sounds like an argument for creationism, but it's because I'm an atheist that I find the question so frustrating/compelling.
Yet, if nothing existed, there would not be anyone asking the question. This doesn't actually answer the question, but it is funny to think about.
Many years ago I read a non-testable hypothesis that stuck with me. What is the simplest, most parsimonious explanation for why this universe exists? The most extreme end of simplicity would be that every self-consistent set of axioms forms the universe that can be derived from it.
For example, a universe may exist consisting only of the empty set. Another universe may consist of the natural numbers up to 42.
Our universe, with a significantly richer set of axioms, has led to an abundance of the hydrogen atom. And we all know that hydrogen is a colourless gas that, if left to its own devices in sufficient quantity and for long enough, progressively transforms and starts thinking about itself.
This is called the Anthropic Principle. I believe you can take it further, in that universes that develop intelligent life may develop the technological capabilities to create new ones (e.g via powerful colliders).
See also this review: https://link.springer.com/article/10.1007/PL00006261
They essentially propose that RNA molecules would be ligated to a small number of amino acids and would then use them for catalysis, and from there evolved the ability to create proteins that are not covalently bound to RNA. So this bridges the RNA world with the RNA-peptide world, and from there it's much easier to conceive of how we arrived at modern biology.
There's a good reason to think that this was the path, since in all organisms today, tRNAs are ligated to single amino acids during translation.