In order to corner the market you must have enough capital (USD GBP LTC whatever) to buy up any bitcoin that gets offered below a certain price.
So it's not a matter of holding enough BitCoin, it's a matter of holding enough cash to buy up any bitcoin that gets put up for sale.
hmm... the situation is a little different then with commodities I think, because you do need some circulation because that is where bitcoin derives its fundamental value. But yes, you'd need to allocate cash to buy the mining injection and big dumps. Or expect that the price will top out when the growth rate = coins mined*price. But buying up the dumps would be not so much "buying" as market making -- taking someone's dump and spreading it across time and at your higher price...
But since BTC is still inflating pretty rapidly maybe this is what's stopping someone from attempting a cornering right now...
at the same time, you have the exponential adoption curve so your worst case exit strategy is simply to wait until that catches up with your price. Your risk is anti-bitcoin legislation, and to a lesser degree a competing coin. You stabilize the price which is good for merchant adoption, which feeds back into the price...
