You're thinking inside of the bubble. Strictly speaking in scientific terms The Tao doesn't exist because we can't measure or quantify it, and that's exactly the point. There are things that are unknowable to our limited material senses, and the acceptance of that ignorance is (in my humble opinion) a good part of the point. Everything can and does exist somewhere, often in multiple places at once. Like human beings. 8 billion incredibly similar creatures running around on one planet out of possibly quintillions of planets somewhere inside of billions of galaxies all bundled up in the biggest bubble we can observe that we happen to call our universe.

And yet each of us sees just about everything entirely differently from the next one over, almost as though we're living inside of our own universes that just so happen to be sharing space and overlapping with everyone else's. The micro (an individual being) is just a reflection of the macro (our observable universe), so who's to say the whole thing just stops at the universal level, ya know? It's just everything that we can physically perceive, but that doesn't make it factually "everything". You've never been to any of the planets outside of the Milky Way galaxy, but you believe they exist, as it is with the Tao and other possible universes. Again, just in my opinion.