$ 11 million is not enough for big investors. There are people who have invested in bitcoin much more. But the problem with these people is they did it much later. After the price of bitcoin has gone up and so they are unable to make a profit of 1000%. I admire the courage of Winklevoss twins. They invested in bitcoin in the most risky time. They deserve their reward.
Tell me then what's considered a big investor? 11 million USD seems a very lot to me and something that the majority of us wouldn't even get in the 2/3/4 etc lifetimes. Remember, the limited amount of Bitcoin it doesn't really depend on investors as much as traditional currencies because it can be mined instead of investing USD.
11 million is a drop in the ocean for GBP and other currencies, but that's just because of the amount of it available. Bitcoin is much more limited in that regard.
I actually meant by the serious money is that the bigger/billionaire investors are hopping in the market.