It is decentralized so in essence no one entity controls it. That is the basis and ideal of crypto currency operating in an ideal world. I think the control is to the people who actually owns the coins and holds it. Do lon as there are many floating unsold coins or coins that are just basically sleeping then you will see substantial movement from it price wise.
I think the major controller of cryptocurrency is exchange because once you listed your ICO in exchange then you have no control on it. Many cryptos together make crypto market and I can say that crypto market is controlled by exchanges. On the other hand I can also say that big whales also control the market because they can change the prices of different coins.
May be you are right that crypto is decentralized but decentralization doesnt mean that nobody can control the crypto market. If there is no one to control the market then who fix the prices of coins. I admit that there are some monopolists who control the crypto market and fluctuate the price as they want. Big investors never let small investors to make money.