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.
Anyone that dies without giving control of the wallet that they're hodling their Bitcoin in to their heirs are doing the network some good because they're making the scarcity of Bitcoin to increase and this is adding to the value of Bitcoin. The more Bitcoin that gets lost, the more we get more demand than supply in the market. For those that are wise and have looked for ways to pass down their Bitcoin to their heirs, they're still positive impact to the industry because they're helping in the continuation of Bitcoin adoption. For those that don't have a strategy in place for when a tragic like death happens, there are multi signature wallets that need two more keys to open the wallet. This type of wallet can be used as an inheritance for when you die.