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?
I think it possible. if that someone has a lot of money to use to manipulate virtual currency market once they sold or bought a huge stock of virtual currency its market will surely change and people will follow with the change. but, it needs big money to do it.
Yes it is possible but i think that it is now becoming difficult, because the use of crytpo currencies is increasing which is also increase the price of crypto currencies, i think that in future it will even become impossible that even big whales will not be able to use to manipulate any single crypto currency.