Wallets owned by the Dead, coins lost forever...

I was just hoping to open up this conversation Harding coins that will never be retrieved. I'm not looking for anyone claiming to have a solution... Much like the hundreds of coins that are in landfills, I am just curious if there is any estimation regarding coins that were owned by individuals that are the walk around and left no Trace of access.
Yesterday was the birthday of my best friend who died pre-pandemic. Met up with a mutual friend today at the grave site just to shoot the shit. He mentioned that our late friend had about a dozen whole Bitcoins that are now lost forever.

How are such coins calculated into the market cap? I believe a good number of coins were owned by individuals that had troubled lives and died prematurely. Obviously, a bunch were also owned by individuals that died naturally but realistically not many senior citizens at hospice care have digital wallets that will be lost after their passing.