I think the biggest upset that billionaires cannot do is the most important thing money should buy. Billionaires cannot afford his own biological children without risking his whole wealth. In particular, billionaires cannot simply afford many (say, 20) biological children.

Okay some comparison.

There are 2 types of billionaires. Females and Males. Obviously female billionares cannot have 20 biological children, nor can they do so on 1900. So let’s ignore the trivial case.

In 1900 China (not sure about europe), it’s simple. Have tons of concubines. Have tons of children. Period. It is easily done. Many are actually doing it.