In most cases, they don't rob you; they demand ransom from your people in return for sparing your life. So, whether it's 15 Million USD in the bank or 15 Million USD in Bitcoin, announcing any sort of financial holdings publicly or even to people in your gatherings is a big mistake, considering how the world has become a place where people only care about money these days.

I don't understand why people don't take simple safety precautions when they know they have so much money and they still keep it in exchanges, roaming around the city while having the exchange in the phone they have in their pocket all the time. Even if you are not robbed, you can still lose your money if you lose your phone and someone with knowledge about cryptocurrencies gets their hands on it.

Just keep your funds either in a non-custodial wallet, or keep your financial apps hidden or locked or something, or simply don't take the device you have the funds in when you go out.