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.
Indeed. I noticed that the "whales" don't pump or dump only one crypto currency. They always sell all of the different coins they bought, lest other traders trying to keep their money will jump to another crypto currency. If the global capitalization of the crypto exchange markets will be enough large, it will be more difficult to manipulate the prices of the coins, but I guess the "whales" can do much anyway.