If an entity is large and powerful enough, is it possible for it to gain a monopoly advantage and manipulate the rises and falls of the virtual currency market?
That's possible if an entity can own majority of a certain coin like bitcoin, but seeing the current distribution of bitcoin by this time, it' s quite impossible for a single entity to acquire the majority. As far as I know bitcoinbis now distributed througout the world and no one can even trace the ownership or exact place where majority of this coins belongs.