If it's interesting, and the ideals are nice, how does it have no value?
If the network participants obtain an utility there is value. One example that I commented several times here in HN: I live in Buenos Aires, Argentina, and when foreign customers paid us via a wire transfer the inefficient big banks (that exist almost everywhere) calculate an exchange rate that is not very fair. Doing the same transfer by Bitcoin and converting it (100% legally) to our local currency gives us a better rate which means more profits for our company. Other examples exist but at the core what is happening is that there are financial innovations that the regulatory framework is killing and can be leveraged with these technologies. Sure, there are a lot of scammers right there but this is another topic.
If gold loses its value, then it's just a heavy rock. They both take time, money, and resources to mine but neither of them have any intrinsic value.
I think the more honest measure is simply how many people have faith in it. Bitcoin and gold may be logically equivalent for this function, but a lot more people have a lot more faith in gold.
But as far as recent technology goes, Bitcoin's been around for a while. It's older then the iPad.
You can't do anything with Bitcoin if is exchanging at $0 USD.
Ethereum is a better example, but on the flip-side so is steel.
Essentially, they are a verifiable ledger of anonymous people exchanging bytes. They may have paid for those bytes with a real currency, much like someone paid for tulips some time ago, or they may have won them for verifying something on the ledger.
Some people in the tulip craze actually had tulips though, right? If a cryptocurrency falls to $0 USD exchange then all that is left is a digital ledger.
"At the peak of tulip mania, in February 1637, some single tulip bulbs sold for more than 10 times the annual income of a skilled craftsworker" [1]
I wonder if time of year plays into the psychology of this.
[1] https://en.wikipedia.org/wiki/Tulip_mania