Apathy is the biggest threat to Bitcoin. If no one cares about any of the cypherpunk and sound money ethos from which it was born, Bitcoin will be co-opted; it's rules will be changed and it's immutability will be called into question.
Maybe this takes 4 generations, maybe 8 or 16, but it will be an ever present threat to Bitcoin that we, the people, will need to remain vigilant to protect.
