" Personal computers were thought of as mostly useless hobbyist technology until years later when spreadsheets were introduced."
"Cell phones suffered a similar skepticism"
The people that invented them could tell you what you might be able to do with them and you'd find that way better than your current situation. Whereas, the design of these cryptocurrencies are worse than our current situation in a lot of ways. The problems they allegedly solve appear to be fixable with better forms of existing technology, law, etc that's used in centralized systems. The people pushing cryptocurrencies never even try to do that. They're ideologically against it rather than looking for whatever solutions are most practical.
So, the potential usefulness of the desktop vs the terminals connecting to shared mainframes/minicomputers or mobile phones vs fixed-location phones is nothing like banks, cards, Venmo, and contracts vs Bitcoin or Ethereum. Actually, the current system works so well at what it does that most people are happy with it. The gripes they have are usually on policies, fees, etc that a non-profit, centralized, customer-focused organization can solve. A series of them cooperating via a standard protocol (i.e. better SWIFT) across jurisdictions and currencies can reduce those risks, too. There's nothing about the problems of current system that makes most people think: let's ditch existing currencies, databases, and accounting practices for decentralized, blockchain-based, crypto algorithms. A solution in search of a problem is an apt phrase.