I look at that graph and think that on the one hand Musk must feel pretty good being on top. On the other hand, though, most of his wealth is tied up in an single incredibly overvalued stock and when the market corrects that interpretation he won't be anywhere even approaching the top. I'd feel much more comfortable being someone like Gates or the Waltons.
Not sarcastic, just looking from a particular perspective. My suspicion is that people with such wild amounts of wealth are way past caring about the material pleasures associated with it and focused on the game. He with the biggest number wins.
In that sense, comfort is about the odds of staying the winner for any length of time, or being unthroned by someone else because you have all your game pieces in one basket.
From the perspective of actual comfort, I assume most of us could be quite comfy with a net worth of a few million. Especially the bottom 90% or so.
