Nice and simple way to explain it. It's also the same reason early miners and holders don't reveal their identity and are extra careful while making transactions. Physical assault for bitcoin is rare but present. There was a real case a few years back in England when someone was forced to give the attackers his bitcoins.
I believe most of the billionaires are already having a good stake of bitcoin, most of these people are smart and they know when they see an opportunity to make money.