That is not the true 3-dimensional vision. 3-dimensional vision is when you can see all six sides of a cube, at the same time. In an "n" dimension, you can only obtain visual information in the dimension of "n-1". This is why if you are on one tip of the "Y" shape, it means you cannot be aware of what is happening at the other tip.
Assume that you did obtain a 3-dimensional range of vision, so if you escaped the plane of 2-dimensionality, and when you looked down from a 3-dimensional space at the 2-dimensional plane? You would realize for the first time that you were at particular point on the "Y" and realize too that there could be another you that took a different path on the "Y"
It's the same for a 3-dimensional space when you acquire 4-dimensional vision. In other words, if you escape this 3rd-dimensional space, and look down at it from a 4th-dimensional space, you will realize for the first time that you were on one point of the "Y", and realize too that there is another you who took a different branch of the "Y" in a different history, in a different world, in a different place.. another you exists. You are omnipresent in the world. We are just branches of "Y".