you can only control the "network" not the price by having a lot of hashrate, and that control itself only goes as far as your share of the total hashrate goes which can not be full control.
here is another problem with your scenario, the more popular bitcoin gets, the higher its price is going to be which is the incentive for more miners to enter the scene which is already gigantic. that means more decentralization of mining power and a much higher cost of someone having 5% of the total let alone a higher percentage.