https://en.wikipedia.org/wiki/MacGuffin
I don't know about cryptocurrencies in general, but ICOs seem to me to be mostly foam.
Fully agree - I don't agree however with how the most popular (which is the reason they're popular)a and how they are incentivized to transfer wealth unreasonably, wealth transferred weighted to the earlier you're an adopter. It's a global, decentralized Ponzi-like scheme. The banking sector are 'adopting' them as any large institution has a budget to try to understand something. All Fortune 1000 companies have money to play around and they'll need to be prepared for blockchain - however don't confuse that with a vote specifically for Bitcoin or Ethereum's Ether.
I've seen it likened to the Dot com bubble. Sure several groundbreaking titans of the Internet were founded during that time. They are valued as major players in the world economy. But there were many more that were inflated and the sector as a whole was inflated.
Now, if you're a savvy enough investor to be able to pick the eventual winners during a bubble, you'll come out great even after the crash. But if not, then you're just gambling. And the house will eventually win.