Instead of playing on our heartstrings to convince us that cryptocurrencies are useful, how about actually making something useful? We've been told for years that it was about to pay off, that "it's still building time". You've had billions poured in ICOs and pre-mined coins and you have nothing to show for it besides glorified pyramid schemes and currencies that are useless as currencies.
Comparing cryptocurrencies to the early internet is frankly absurd. Maybe people didn't imagine how huge is was going to become but the practical usefulness of being able to share data across the USA (and then the world) is obvious. Besides the Internet grew fast and was useful almost from day 1, even though it involved a complex and expensive hardware infrastructure. By the 90's the Internet wasn't mainstream but it was definitely very useful. Sci-fi writers had expected something like the Internet long before ARPA, it's just immediately obvious that being able to connect to the entire world in real time would be greatly valuable.
Furthermore what prevented a more mainstream adoption were mainly hardware limitations. Internet on dial-up wasn't fun at all. Remember having to wait for a full minute to have a progressive JPEG load up? I do. It was clunky but there was nothing else like it. Once technology improved and got faster and cheaper adoption exploded. What's slowing down progress in CryptoCurrency? The infrastructure is there, yet hardly anybody wants to use it. And unlike the Internet, there are plenty of alternatives for the vast majority of the services offered through a blockchain.
>I would bet that we see something truly unique come out of the blockchain space that we never before knew we needed.
That's faith, not reason.