For a start, the vast majority of crypto-trading-cards are held by relatively few people, who therefore have a large vested interest in trying to hold a line in the virtual sand.

According to the New York Times, as much as 95 per cent of the supposed wealth is held by just 4 per cent of the players. The Winklevoss brothers of Facebook semi-fame won't say goodbye to a billion dollars without a fight.

Furthermore, the spectacular December gains by some of Bitcoin's sprogs reek of dubious ramping on thin volume. A manipulated market is often good for another attempted ramp.

But most of all, dead cats famously bounce.

It would simply be too sweet for all the sceptics - out-of-touch fuddy-duddies like Warren Buffett and the world's central banks, never mind whole battalions of economists - to be proven correct so quickly.

At a point in the crypto-plunge, some crazy-brave true believers, a few speculators and the odd manipulator are likely to be keener to buy or hold than those running for the exits are to sell.

And with that bounce, the remaining sane speculators tend to bail out for good, or at least until it or a variant is ramped up again some years down the track.

We're probably due for yo-yos and hula-hoops to have another hour upon the stage.

The excuse for the current dive is the threat of authorities cracking down on what has been a key appeal of bitcoin - its anonymous potential as a medium of exchange.

But the particular excuse doesn't matter. If it wasn't Korean and Chinese rumblings, it would eventually have been something else. That's just the way manias go.

The portents have been multiplying that something was coming along to burst the bubble. For me, the bell was rung by encountering the equivalent of bellboys putting savings they couldn't really afford to lose into the cryptostamps.

That coincided with the sheer nonsense of businesses as varied as iced tea, Hooters and Kodak all seeing share prices jump just for mentioning "blockchain" in relation to their companies. We went through the same charade in the dot com bubble, when companies started using "e" as a prefix.

(And, just like the dot com bubble, the actual technology of distributed ledgers will kick on and be useful in many applications - just not as a tool of the dark web.)

Crypto-copycats

The surest indication that the bitcoin mania would be brief, however, was the proliferation of wannabe distributed ledgers. With every new "currency", the rarity value of the breed was diminished.

There is no limit on the number of crypto-copycats that could start a mine, but there's a definite limit on how many mugs are born every minute.

In time, the laurels for calling the top of the bubble might go to the Sage of Omaha weighing in with his forecast that bitcoin "almost certainly will come to a bad end". That's Warren Buffett, arguably the world's best investor.

Or maybe another billionaire who knew a bit about speculation had it right.