Remember, this whole thing about crypto is largely decentralized, thus, there is no single authoritative body in control of the crypto market. Although there are few centralized platforms among crypto, the market is largely influenced by the efforts and influence of the users of crypto. How well sellers and buyers treat the coins on the market affect the performance of the market.
Nobody controls the market as what you have said. The fluctuation of coins price in the market is due to the supply and demand which makes the price varies from time to time.