Comment by LanceH
I know nothing about this specific situation, so I'm not speak to that. I am speaking to "why keep your wealth as cash in a safe?"
I'm old enough that grandparents lived through the great depression. I know they kept wealth in a safe. A lot of their kids did as well. The grandparents had their gold money taken away, or their cash disappeared in banks. A lot of their kids followed along.
Being gen X, Elon has parents/grandparents that lived through the great depression and world war. That along with any other local factors makes keeping wealth in a safe not that unusual.
Elon Musk grew up in South Africa.