I see a lot of Krugman "bashing" in threads like these. But please let's not forget that Krugman fulfills an important function:
He is the representative spokesperson of the System. The system which consumes and destroys our future, progress and happiness and which will not stop until life itself is extinct.
As such, we should pay close attention to what Krugman says, since he is the closest line of communication to our most mortal enemy. And it reveals their thinking...
He does not represent "the system" as it is today, he represents a small but growing element within the system that wishes to return to the capital controls of the 1940's-1970's. This is why he also dismissed the Internet, since international trade in goods and particularity services at the retail level is incompatible with capital controls. Ever wonder why PayPal was forced to suspend domestic transactions in Argentina?
http://www.bbc.co.uk/news/technology-19605499 I still remember going through customs in the UK in the 1970's as a teenager and there were signs saying it was illegal to take out more than a certain amount of sterling out of the country. I recall something in the neighbourhood of 10 - 25 GBP. Many young people today do not have any direct experience with this evil which is far worse than most of the "evils" of "the system" today.
Paul Krugman has been a strong supporter of foreign exchange controls
http://www.cato.org/publications/commentary/siren-song-exchange-controls so it is hardly surprising that he would consider Bitcoin evil.
Convertible fiat currencies such as the USD, EUR etc have nothing to fear from Bitcoin, but
non convertible fiat currencies such as the INR, VEF or ARS have everything to fear from Bitcoin.
A convertible hard virtual currency that can be instantly sent across international borders, without the intervention of a bank, is the death knell of any foreign exchange control regime.
This is why Bitcoin has so much potential already: it eliminates capital controls. This is a "killer app" for it. Even the EUR is afflicted as capital controls exist in Cyprus.
Yes this may well turn out to be the killer application for Bitcoin. Just take a look at the response from China and India. Both of these countries have capital controls. One thing to keep in mind here is that if it is illegal for residents of a country to trade and / or hold USD or gold, then expect similar restrictions on BTC.
Krugman deserves to be bashed not because he is part of the system, but because he is trying to turn the system into something far worse.