It's a huge problem and we should never discuss our holding with anyone, just like nobody would ever go out shouting "I have 15 Million USD in the bank".
Even if some millionaire shouts that, thief would have to rob a bank to get to your money or kidnap your family member and ask for money and neither of those things are very easy to do. In the case of crypto millionaire, its enough to beat him up until he gives you seed which is much easier.