The peer-to-peer-ishness probably makes the whole notion academic: Clearly this character would be peerless among mortals.... Sigh, back to the drawing board.
Actually, his powers could be drawn from his relationship to his crew of anonymous "miners".
Better yet, he could be the Frankenstein monster created by a genius (Satoshi) experimenting with genetically modified human DNA, drawing his strength from a nebulous network of mysterious individuals located around the globe. His kryptonite would be the 51% attack on his personal network which his nemesis is always scheming to discover.
Write the script.
Draw the comic.
I want a donation address NOW.