To be fair the guy is ancient and Patagonia wasn't public, so he could only ever take out loans against the company, he couldn't actually turn his shares into cash. It's like owning 2 billion in real-estate on the moon
Isn't there this thing businesses do sometimes that's called "going public", where one puts their share of the ownership on the market for sale, in return for which they receive cash?
Why would that not have been possible for this ancient guy too?