Why is the highest US currency the $100 bill? Why not a $500 or $1000?
We had higher denominations in the past, then they were withdrawn.

With multi-year inflation, it seems that higher denominations would be a good idea.
Las Vegas high-rollers & casinos could benefit with bigger bills.
(Although drug dealers would find the higher denominations useful too!)

By comparison, the highest Swiss Franc is CHF 1000 which equals about US$1100.
The highest Euro currency is E500 which equals about US $663.