[charlesdm]

Except it was likely property, and he couldn't liquidate those properties without incurring capital gains taxes (set at 49% in 1970)?

I don't know, perhaps you couldn't very easily leverage properties back then for cash (i.e. once they had been paid off), or interest rates were very high (a quick google teaches us that in 1970, the interest rate was 8.5%)?

[munk-a]

It actually wasn't property, a large portion was cash in terms of salary collected as an infant or various gifts. There was a report by NYT not too long ago.

https://www.nytimes.com/interactive/2018/10/02/us/politics/d...