I remember my dad always talking about bitcoin back in the day and how it was gonna be the next big thing. Unfortunately i guess he never actually purchased any lol he just talked about it alot. I was young still so i had no idea how to get any but i tried. I just remember signing up for crypto exchanges and being too young to buy damnit! 
Maybe it was a time where your father had no means to actually invest. If he was so passionate in talking about it then he might have really believed in bitcoin and therefore would have bought some but unfortunately it is not always that we get to do what we want.
I also would like to buy more bitcoin and constantly think about it but I just currently do not have the means for it.