Nope, this is no existential question (although...). Everybody's talking about "When will Bitcoin die", but what if you die, and your family don't find your key, or don't understand it, or think it's only a useless sheet of paper with some code on it, or simply throw it away... Does this mean the currency's gone forever?
I find the possibility of this event rather realistic (yup I don't believe in eternal life), so that means that someday there might be 21M BTC but only 18M (and counting down...) is left in the market?
Yes, My wife knows I have bitcoin and other cryptocurrency she has a private key from my account. I have also taught him to open and sell him, I tell him if I die his decision if he will pull all my coins into the fiat for the cost of my death or he can save it for him and his future.