“How are they supposed to become any sort of replacement for currency, precious metals, etc.?”
I agree - I think they will be hoarded. Just think that in 2010 (just 7 years ago) when bitcoins first came out you could have bought 1000 of them with one dollar. That one dollar worth of bitcoins would have made you a millionaire today.
With more and more countries eliminating cash, bitcoins become very attractive for people who don’t want the government snooping into all their financial transactions.
The block chain shows every transaction every made with the coin. Not sure how that can be deemed "safe" from government snooping ...