Pretty smart to leave bitcoins for your children because that will make them rich and they don't have to worry about taxes or anything. But maybe it will be for nothing because bitcoin may always go down and maybe another coin will become important.
It is not that it is for that purpose, that they want their children to be rich, the right way to say that is that they just wanted to give their children a bright future by using bitcoin, though we don't know how long will bitcoin last here in the cryptocurrency world, but yeah, saving it for our children is a bright idea. It is like having a trust fund(but a better one) for our children, even though bitcoin's price goes up and down, still, it is the best coin ever in the crypto world.
Saving it not just for your children but for also to your family is a great thing to do also, because it is better to build a bright future with bitcoin.