I mean a Bitcoin millionnaire should be more careful to protect his private keys.
how? if someone points a gun at you, or you get kidnapped by 5 people, there's nothing you can do. The guy clearly values his life way more than his money, good for him (though it took him 8 hours to realize that.)
Is there any useful system providing that? Maybe in the future there will be Bitcoin banks to save these Bitcoin and reaching to them will require more than 1 password or key...
No one should trust a third party to hold their private keys or their BTC.
Best way to avoid this kind of things would be to not let anyone know that you have BTC, or keeping your coins in several wallets. Simple as that.