I actually know someone this happened to — a guy I met a while back died unexpectedly in an accident. He had a cold wallet with a decent chunk of BTC, and to this day, his wife still hasn’t been able to recover any of it. He didn’t use any kind of inheritance system or trusted setup. It’s just... gone.
It becomes a problem if you do not tell your closest family how to access your wallet. The effort to store Bitcoin for a long time will be in vain without being enjoyed by our heirs. It is actually not difficult to explain that we have assets stored in a wallet. How to access it can be told to the most trusted family members, but the key is still stored. We can tell the location of the key to access the wallet stored in a certain place.