The shares get dispersed to the broader family, children, grandchildren etc.

Typically at those levels of wealth there is a “family office” which is just a word for “hedge fund” that’s only clients are the family. Like any hedge fund they can use those shares as parts of lots deals to diversify, manage risk and pull out cash.

Sometimes it’s even simpler, dividends can provide a significant cash flow for large shareholders.

In any case, it would be extremely strange for someone to get very wealthy and then hold most of their portfolio in cash.