Nothing and something are two properties of one quality: the state of being. Insofar as you can assert that existence is a "property in itself," all things can be said to either exist or not exist. But this is not born out by evidence. There is an infinite division by degrees of "being" between nothing and something, which we can call "0" and "1" respectively. Take, for example, an apple. Would you call a full, unmolested, ripened and plucked apple an apple? What would you call it if I took a bite out of it? Or what if I ate the entire thing? At what point, in other words, does the apple cease to be an apple, or changes properties and becomes something else entirely? Since I do not eat the apple all at once, even the change in property is gradual. We can perhaps say that an apple with a bite out of it is 90% apple, 10% not, but unless there is a sudden watershed moment between apple and no-apple then it is a matter of degree. Nothing is truly "apple," as that is meaningless; it can at best be said to be "mostly apple." Perhaps more rigorously, we can say that the space formally occupied by apple-stuff is mostly apple-stuff. The key takeaway of this exercise is to illuminate that there is no fundamental difference between existing and not-existing. Or to be more clear, something and nothing. It is mostly a matter of degree. And since you insist on using a tautology to demonstrate that existence exists, we must apply with equal rigor to this qualification what we do to that of the apple. That is to say: existence mostly exists (depending on your associated axioms, anyway). This reasoning can be extrapolated to include your theoretical "all things exist because existence exists" and I presume you see where I am going with this. All things mostly exist, or most of all things exist, perhaps. The exact dimensions are unknown, but it does not demonstrate a fundamental change in quality to have some things not exist while other things do. Something from nothing, in other words.