As we know Bitcoin is digital crypto currency, investing in Bitcoin must be kept secret. In addition, there are countries where Bitcoin laws are not valid, so more caution should be taken for those countries.
In the country that bitcoin is prohibited, then you have to be very careful. It's best to avoid discussing bitcoin with strangers unless you know them well, as there are covert government agents out there. You might be arrested and jailed if they find out that you have invested in bitcoin. If you live in a country where it is illegal to own bitcoin, you must keep your head down and keep your possessions hidden from others.
In a case like this, I would recommend having some sort of decoy wallet, and hope that the attacker/kidnapper (or relative in this case) finds that amount enough... You could even tell them that it's all a lie, and all you have is the amount in the decoy wallet... and that you only wanted to brag a bit about it
Don't you think your life will be at risk? Or do you think that after showing them a decoy wallet, the kidnappers will just free you and ask you to go? They are still going to demand a ransom, and if you cannot pay in bitcoin, they will ask you to pay with fiat currency. If you cannot pay, your life will be at risk. The best thing is to never tell anyone the amount of bitcoin that you are holding.
Some people just don't know how dangerous this is and want to show off. There are a lot of stupid people around, we can just do better and try to teach them.
It's not that some people are showing off, some people do end up telling people about their investment just because they are trying to convince people to invest in bitcoin. If you are trying to introduce anyone to bitcoin, then you know you have to use your wallet as an example. Just tell them the basic things about bitcoin and the importance of bitcoin, and tell them you are also holding some bitcoin. But some people will show their wallet to encourage or to make people believe them, which is very wrong.
When introducing anyone to bitcoin investment, you don't have to force anyone to invest in bitcoin, just tell them what you think they should know, and that's all. It's left to everyone to choose whether to invest or not. Don't put your winning investment or your life at risk just because you are trying to convince someone to invest in bitcoin.