If you’ve ever wondered what “cryptocurrencies” such as bitcoin, litecoin and ethereum are for, ask one of their legion of techie-libertarian fans.

And it’s dollars to dogecoins (yet another one) that the conversation will go something like this:

You: So what’s the purpose of bitcoin BTCUSD, +0.05% ?

Fan: The technology is absolutely amazing!

You: Yes, but what’s it for?

Fan: Really, the “blockchain” technology is a total masterpiece, way ahead of its time!

You: Yes, yes, I understand that. But what is it actually for?

Fan: You don’t understand! It’s a completely decentralized money system! Totally revolutionary!

You: Honestly, does it have a purpose? Any purpose at all?

Fan: It’s the wave of the future!

And on it will go.

It’s now an $82 billion market

Cryptocurrencies, or cybercurrencies, which were in a massive financial mania until their sudden selloff that started last month, have two actual applications: online gambling and money laundering. Neither is the heart of a major business model. But that’s it.

And these, preposterously, are the fundamentals behind a mania that has driven these currencies up thirtyfold, so that today, in aggregate, the market for them is a staggering $82 billion.

None of the defenders’ other arguments stack up.

Online currencies are hardly a “store of value” when they can fall, say, about 30% in a week.

Are they really protections against the ravages of “inflation” and “monetary debasement” imposed by wicked governments? If so, how come people who keep their money in bitcoin and ethereum and the like have experienced Weimar Republic levels of consumer-price inflation in the past month?

That is, after all, what it means when the price of your “currency” plunges. Ethereum isnt just down 50% against the dollar since mid-June. It’s down 50% against the potato, the sack of rice, the gallon of gasoline and the new car.

Read:Ethereum has lost $17.5 billion in market value in 4 weeks

Pure speculation

Admittedly, before all this, the price of these cybercurrencies had skyrocketed. Those who got in at the start of the year had previously turned $1 into $30. But this looks more like a speculation than a currency. And what will tomorrow bring? I have a pretty good idea how many potatoes I can buy with my dollars next week. Bitcoins? Good luck with that.

You notice, incidentally, that these bitcoiners continue to measure the market price of their beloved new currencies in terms of, er, old-fashioned U.S. dollars.

Cybercurrencies may make online purchasing and international money transfers marginally more efficient in theory, if hardly in practice. Would you risk moving your money from dollars into bitcoins just to save a few percentage points in transaction fees? You’ve seen that wiped out many times over just in price fluctuations.

Competition from all sides

Bitcoin, the granddaddy of them all, might at one point have claimed value as a unique entity. If it held a monopoly among the people who wanted to use a cryptocurrency so they could play online poker or finance international crime, it would have some worth. Yet in the past few years multiple competitors have erupted. There are now 25 with individual market values above $100 million, several above $1 billion.

Fast-growing rival ethereum was worth bupkis at the start of the year. Today it’s valued at $20 billion, or almost seven times as much as the company ESRT, -0.16% that owns the Empire State Building.

Preposterous? You make the call.

This article was first published on June 15 and has since been updated.

Read on:Bitcoin needs government regulation, says Morgan Stanley

Also:The chart that points to ethereum overtaking rival cryptocurrency bitcoin