Yeah the graph is more for vibes than an actual analogy. The yellow slice represents the top 1%, purple 90-99%, green 50-90%, and red bottom 50%. It would make a bit more sense if those slices were labeled "1 person", "9 people", "40 people", and "50 people" respectively.
Even then, the numbers don't even remotely work out. Consider this "Elon Bezos" person; the combined net worth of Elon Musk and Jeff Bezos is about $1.3 trillion or so, and the "Top 0.1%" category in the Fed's data has a net worth of about $25 trillion. This is not a small difference.
Sure. Hedge fund owners, VC firm owners, cosmetic surgeons, the Walton heirs, and Zuck/Jensen/Jeff/Elon own 97.5% of all wealth in the United States. The former three, while each representing cohorts, are very small cohorts. The latter are billionaire individuals.
If you're an American and not among those specific groups, your share of the remaining 2.5% is split with the rest of the US population in that slice (i.e., the overwhelming majority of the population). It's an illustration of our extreme wealth inequality. (Whether it's an effective or good one is a matter of opinion, but I do think it broadly conveys what it intends to.)