Is there any evidence that these mysterious 'whales' really control the bitcoin market, or is this a myth generated as people try to understand why bitcoin prices go up and down?
Maybe there is. But then again - it's just a theory, as is the theory that the world is ruled by several influential families. The market is manipulated-and quite easily! Plus, there are a lot of bots trading on crypto-currency exchanges, arbitrage bots, which can be programmed to push the price in one direction or another. There may be a certain collusion, but it does not always work! Market factors which arise subsequently, error, panic sales, or HYIPs which give a snapshot of growth is impossible to predict, and they emerge naturally.
I dont think it just a theory. You can see over in bitcointalk peoples are making their pump group gathering their army to pump the coins up. Choose some low market coin and pump it up and dump it are not that hard right. If it bitcoin they need like billion to pump it up and that not impossible also. So the rich are getting rich the poor will suffer from the act. It will the same forever.