Loco Steve / Flickr, CC There is a great op-ed in the Baltimore Sun that argues Bitcoin is useful mostly for criminals. E.J. Fagan, the deputy communications director at Global Financial Integrity, a research organization dedicated to studying illicit financial flows, argues that the only people who really need completely anonymous financial transactions are criminals.

If you're a non-criminal, you don't need anonymous, untraceable financial transactions, Fagan says. Or you could use cash, which is still almost completely anonymous.

But criminals have a different problem when it comes to cash. Once your criminal business becomes successful, say from dealing drugs or running sex slaves or poaching rhinos, then the cash really starts to pile up. Although criminals in movies like to put cash into paper bags and fancy briefcases, this becomes very impractical, very quickly.

Criminals need banking services, basically.

But criminals hate banks, because banks tell things to the police. Bitcoin basically solves the banking problem for criminals, Fagan argues:

By largely eliminating intermediaries, bitcoin allows individuals to conduct transactions without being subject to anti-money laundering controls, which makes it an attractive currency to criminals — particularly those who prey on the weak.

... Criminals need bank accounts, cross-border transactions, and — mostly importantly — anonymity, to execute large-scale transnational crime. Bitcoins essentially allow criminals to make peer-to-peer cash transactions at enormous scale.

... [Anonymous online currencies is] help criminals launder massive amounts of money. More girls will be sold as sex slaves, more rhinos will be poached, and every other large-scale transnational crime that you can name is going to become a lot easier if criminals have a way to transfer very large amounts of money completely anonymously.

There is anecdotal evidence to back this up. The Bitcoin exchange market has become rife with hackers and "bank" robbers. And Ross Ulbricht, the alleged master of the Silk Road market for criminals, amassed a fortune of $20 million in Bitcoin, which he was using to pay hit men to assassinate his enemies, prosecutors claim.