With that much money, you would not need build anything. Just buy all the Bitcoins that people are willing to sell, that alone would be enough to control it because there is a limited number that will ever be produced. The market values you read about have quite a bit of fluff to them since people having to be willing to purchase it for that amount, let alone sell it.
That won't change much lol. Simple money supply tbh. Bitcoin would just be boosted through that one would think.
If the value was 3 or 4 more times, who would actually buy it? And bitcoins are not infinitely divisible. Miners would be hurt the most because it would push them to mining for 0.0000001 transactions which would overrun the fees. From a mathematical standpoint, buying the larger amounts nets investment at the expense of the miners. It's not economics but mathematics that would rule out that scenario. 
