Maybe he has nothing to do with being a Crypto Millionaire and something else that you aren't aware of nor the media? He isn't the first millionaire I guess? There are thousands of them in each country and the source of income doesn't matter if it's real estate or Crypto, this sort of thing can only happen if there was a fight between two people or so. RIP, no one really knows what happened except the family who can access his phone.
Not quite, crypto-millionaires are potentially the best targets for criminals. It's way easier to force someone at a gunpoint to transfer their crypto than to transfer their fiat (banks would restrict that + transactions can be reversed or traced to account owners), not to mention transferring wealth from the real estate.
Of course, you could "protect" yourself by say storing your seed phrase somewhere safe, but if the bad guys believe you have instant access to $millions worth of coins, you might still end up tortured or killed.
Another angle is that many of the crypto millionaires got rich overnight and are simply not used to handling their new situation in terms of security etc