I've heard many of my companions say the bitcoin is the greatest invention in the decade.. But I wonder why every country don't accept this as a legal currency in their general transactions?
I think, that thing is directly related to cryptocurrency like bitcoin which is decentralized, there is no interference from the central authorities like the government, also, cryptocurrency like bitcoin allows people to trade directly with each other (peer to peer), meaning that it cuts the need for intermediaries, which is traditionally a bank.
Because That reason, many countries prefer to prohibit it rather than accept and make it legal.