[Scene_Cast2]

So I have a feeling that he's looking at the wrong histogram. If you plot the distributions of the vector magnitudes, you'll get a spike around whatever large number, and a very sharp falloff to the right and left.

However, it's not a "bubble" in the intuitive sense. He's looking at the magnitude distribution of dots over the entire space, and implicitly using the Cartesian coordinate system (discarded angle, looking at just magnitude).

If you look at the distribution of dots per volume (or R^N hyper-volume rather), then you'll still have the highest concentration in the center, with no "bubble".