Earlier quoted context omitted.
In a way, bitcoin itself is not really a currency, or money, it's more like an idea for exchanging messages. Bitcoin is really a decentralized messaging system which relies on cryptography and proof-of-work to maintain integrity. Should exchanging messages in the form of "I owe you x amount" over a p2p network be regulated or be made illegal? However, The fact that it's used as a form of currency is just an interpret…
They are also disastrous for the planet - bitcoin's carbon footprint is growing, trading our planet for ... imaginary points. This has got to stop.
Current estimated power consumption of the Bitcoin network: 1.67 Mega watts. (6,028.57 megawatt hours http://blockchain.info/stats).
Typical power generated by a single Boeing 747: 140 Mega Watts. There's hundreds of these flying right now, yet no-one is appalled about the carbon footprint. http://en.wikipedia.org/wiki/Orders_of_magnitude_(power)