The grandfather was displaying some wisdom. 15 years is small potatoes when you've seen say, 40 come and go along with all the things that were hot being no longer hot. Some day, some how, the Man on Monkey island won't come back. It might be a hell of a ride until then--but some day that story is over and something else starts. It's not about Bitcoin exactly. It's a fact of life and what is valuable in one period of time becoming worthless in another.