Hmm, you can't hide that much imo. Even the richest families of old have a couple of billions at most.
Globalisation and open markets make it easier today to make a lot of money compared to back when the wealthy were mostly royals and other nobility.
The richest man ever, inflation-adjustment included, was John D. Rockefeller with roughly 336 billion back in 1913.
After his death, his fortune lasted a few generations but as usual, it mostly evaporates due to both mismanagement by family members that have no experience handeling that much money and changing times.