Even after the FED broke all promises and broke the dollar's ties to gold, there were so few people willing to still use gold as money in daily transactions that gold never regained its true value.
The edict backed by the world's superior machinery for causing harm did a long way as well: "10 years of prison & 10k USD in fines to anyone who dares even possess gold."
This is largely why I think so many in government and banking do not see bitcoin as a real threat to the system. The mind set there is they have a multitude of methods to dictate and control money as they see fit. It's why bitcoin as a real threat is considered to be a joke in many of those circles.
And although I disagree with them (it's why I am here), the threats are real and I personally think bitcoin should constantly be thinking about how to strengthen itself against them.
Take chainanalysis's likely recent Sybil attack. This is a small startup, there can and will be bigger attempts and may things in the future.
https://bitcointalk.org/index.php?topic=978088.msg10756505#msg10756505