Good arithmetic here, but: There is a reason the welthy, and most other people for that part, have little money and lots of stuff. The reason is the inflation. What you call appreciating assets, is mostly inflation-safe assets. With sound money it is different, you don't have to panic buy these assets, therefore the demand for sound money might be higher than for fiat money, supporting a higher money value.
The point is that even if someday Bitcoin is worth more than all the currency in the world that is still a small fraction of all the wealth in the world. Your house isn't made of currency, Google isn't made of currency, the patent for a new drug ins't made of currency. They all contribute to the wealth of the world though.
I still believe that Bitcoin becoming the single world currency is a dubious and highly unlikely pipe dream but lets say it happens. Even those with massive Bitcoin holdings would still have a rounding error of the wealth of the world. Unless they plant to eat Bitcoins, watch scrolling screens of private keys as entertainment, and sleep inside a Bitcoin they are going to liquidate some of the wealth (which is already a rounding error on total global wealth) to buy food, entertainment, housing, etc.
I tried to address this point a few posts above. I also have to say, it doesn't really become clear in my original post because, well, I didn't really think of it that way yet when I wrote it.
The point is not so much how big the share of the total wealth is, now with "traditional" billionaires or in the future with bitcoin "billionaires", but about the
ratio between percentage of wealth owned now, and then.
Follow my assumptions in the original post for a second, okay? Then my point is, the current richest person holds at most 0.1% of money supply (yes, only money supply, not overall wealth). In the brightest of all bitcoin futures, someone might hold more than 2% of money supply. So the point isn't that 2% is too much, but that this would constitute a 20-fold increase in relative wealth. That's at least worth thinking about, IMO.