It is why all should be sure to be sensible and make copies of private keys and leave them either in secure places or with family members they can trust.
Family can be your worst enemy in some cases. Everything that involves a lot money changes people from good to bad instantly in certain situations. If you need the money badly, and see that you have access to x number of coins, for a lot people that will be an easy choice and option. If you want your family to at least have something, set up a fiat fund, or one that you can include a fair number of coins in. This all will get released once you're gone, and investigation has turned out that you have died naturally, and not poisoned or whatever by greedy family members. It's quite complicated, but every person will deal with it on its own way.