Haram means illegal, I don't see any special and logical reason behind the bitcoin is illegal. Day by day it's gaining popularity among the people who engage in virtual work. So i 100% believe that its is totally contradict the people idea about haram of bitcoin because its 100% halal (legal).
Bitcoin is a currency.
Dollar is a currency.
Pound is a currency.
Euro is a currency.
All other fiats are currency...
Dollar, Pound, Euro and all others currencies are Haram?
I leave you to justify your statement yourself.