Even with those fluctuations, you can live (more than) comfortably with those $100 billion (probably). Unless you're being sarcastic
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.