crucial feature of these currents is that they are largely untraceable. at least until very recently. every successful technology fills some need or solves some problem. what is the need that cryptocurrencies fill. it is not to buy and sell on the web or to move money electronically. all of that could easily been done using transitional financial institutions and new interfaces like paypal or apple pay. but none of these could replace chateauing transactions that take place in the analog world where one person hands another a bag of cash. that transaction is inefficient but secret and largely untraceable. cryptocurrencies allow you to do something similar but digitally. no, this is not a matter of a private discrete payment, see a man would wants to book a hotel in paris for a weekend without his wife knowing.