For years the conventional wisdom in finance has been that bitcoins are a silly technological game, a bubble, and a fad.

Today: Not so much.

Bitcoins have just gotten serious, and people are going to have to start paying attention to this digital currency. That means investors, governments, and those trying to fight crime as well.

This was already true even before the news out of California that criminals just used bitcoins to extort $17,000 in blackmail from a hospital and make, so far, a clean getaway.

Bitcoins are booming. They have doubled in price in the last six months. Indeed bitcoins were actually the best performing currency in the world last year. I ran an exhaustive screen on FactSet, making sure to include everything from the Afghanistan afghani (down 16% against the U.S. dollar DXY, +0.02% ) to the Zambian kwacha (down 42%). Bitcoin trounced them all. The dollar value of each bitcoin jumped 40% during 2015, from $310 to $434. (The currency in second place, the Gambian dalasi of all things, was nowhere near: It rose just 9% against the U.S. dollar.).

At current prices, the total value of bitcoins in the world now tops $6 billion. That’s quite some “fad.”

Is the $100 bill endangered?

I wrote recently about how bitcoins could allow anyone in the U.S. to make a mockery of our (admittedly ridiculous) online gambling laws. The Federal government — and its overseas counterparts — wields tight supervision over the transfer of dollars, yen USDJPY, -0.15% , pounds GBPUSD, -0.42% , euros EURUSD, -0.06% , or even Albanian leks through the traditional banking systems. So-called “anti-terrorist” and “anti-money laundering” measures that were hustled through in the panic after 9/11 have basically ended financial privacy.

But right now, nobody controls bitcoins — and so far they haven’t been able to do much about them.

Bitcoins are hard to get your head around until you’ve used them. (Alec Ross’s new book, The Industries of the Future, contains an admirable section explaining the technology.) But in a simplistic nutshell, you can go online and exchange your dollars for bitcoins, transfer those bitcoins anonymously to anyone, anywhere in the world, and they can then exchange them back into dollars — or leks, or yen, or whatever.

“ The bitcoin infrastructure isn’t controlled by any entity. ”

The entire transaction takes place outside of the banking system. No one has to show any ID to anyone. The exchange rate for bitcoins is set by a freely traded market. And bitcoins have value for the same reason that dollar bills and gold coins have “value” — because lots of people think they do, and they know that other people do as well.

What really matters is that the bitcoin infrastructure isn’t controlled by any entity. Not one government, not one company, not even one cooperative. It uses an incredibly ingenious and complex set of programs running on a giant network of independent computers around the world.

Bitcoins are the Matrix. They are everywhere and nowhere. And they’re going to be a problem for regulators.

Because right now the world’s governments are trying to tighten their regulation, supervision and control over any and all transactions bigger than buying a pack of gum.

This week Harvard professor and establishment mouthpiece Larry Summers joined the fight with a call to scrap certain “big” denomination bills — such as the $100 bill, and maybe even the $50. The reason? They make life too easy for criminals. Cash is anonymous and portable. Summers wants to restrict its use really to small bills used for small transactions.

He is far from alone. Some of Summers’ Harvard colleagues just published some detailed research on the subject. Governments as far afield as Switzerland and Singapore have stopped printing really, really big bank notes — like one worth about $7,000 — for the same reason. The European Union is considering scrapping the 500-euro note.

But while the establishment tries to tighten the screws on the anonymous “cash” economy and subject everything to closer and closer regulation, bitcoins are a perfect example of how things can slip through their fingers.

Hackers broke into the computer systems at Hollywood Presbyterian Medical Center earlier this month and crashed them. The hospital said this week that it was so desperate it bowed to the hackers’ demands and paid them a ransom — of 40 bitcoins. The value was just under $17,000.

The bitcoins were transferred to an anonymous online account with a click of a mouse. No big black bags. No unmarked bills. No getaway car. No chase. No exploding blue paint. Click, and that’s it. It’s a cyberheist.

The money trail will still leave digital footprints on the web, and the FBI is surely following those right now. But if the criminals were clever the investigators will eventually reach a dead end. The criminals will be caught only if they made a mistake.

There are plenty of legitimate reasons why someone would use bitcoins for a transaction. It can, for example, be an incredibly quick and cheap way of transferring money. It can be especially useful if you are sending money to relatives in a poor country where the banking system is poor. It can allow you to do things anonymously that are legal but which you prefer to keep private. And in a free society, freedom itself should not need a justification. The burden of proof is on those who would ban something.

Yet bitcoins, like cash, can also be used for nefarious purposes.

The recent Harvard study suggests — guesses, really — that about $3 trillion changes hands each year in international money laundering, drug dealing, terrorist financing, corruption, and other crime. Most of that involves cash. If they can’t use cash, some will find another way. Some will use gold. Some will use one-carat diamonds. Some will use London real estate. And some will use bitcoins.

If bitcoins are used for just 1% of international criminal transactions that will come to $30 billion a year. The current $6 billion bitcoin monetary base would be turned over five times a year — or bitcoins would rise in price, increasing the size of the base.

No one is sympathetic to international criminals. Least of all when they are engaged in things like terrorism, human trafficking, or blackmail. You have to be especially sick to attack the computer systems of a hospital. And so this is a problem.

But the government doesn’t have clean hands either.

Governments always seize on brief panics and outrages to demand greater restrictions on civil liberties — which they then abuse to harass regular Joes and Joannas.

For example, a law passed 50 years ago specifically to tackle a small number of extremely rich criminals is now being openly abused by the Treasury to persecute millions of law-abiding middle-class Americans who live abroad. The laws passed after 9/11 to tackle the financing of “international terrists” (sic) were then abused to stop people paying $10 craps games on the Internet. Laws put on the books to stop money laundering were abused just last fall to secure criminal convictions against former U.S. House of Representatives Speaker Dennis Hastert. His “crime”? Paying a blackmailer. With his own money.

Bitcoin is going to be the next battle over financial regulation and civil liberties. And don’t be fooled. There will be arguments, and lies, on both sides.