I strongly believe that if some well known investors come in and buy billion dollars worth of bitcoin it could be world breaking news and the price of bitcoin would soar high to $10000, just my opinion.
You are quite wrong with your prediction, bitcoin already have $41 billion marketcap so addition of just few billion $ will not make huge pump to $10000 and I think there are many multi billionaire out there who have already invested in bitcoin.
Marketcap has nothing to do with it.
It depends how many people will sell when 1 billion dollars hit the walls.
For example if only 10 persons will decide to sell 1
BTC each the billion $ will rocket the price to 100 millions.
If everybody decided to HODL....the price will go to ∞