say that suddenly out of no where, bill gate and warren buffet both decided to sell everything and buy bitcoin
so they both got like 120 billion dollar
say if both of them go to the exchange and buy 1 bitcoin = 1 million dollar, they can only manage to buy 120,000 bitcoin
but as far as you know, there are 12 million bitcoin in circulation and if 10% bitcoin want to sell off for 1 miliion each, you have 10 times the supply over the demand
you can only wish that only 1% of the bitcoin in circulation wanna sell of at 1 million each so you can sustain the price for like a few seconds
so the conclusion is
NOPE, wont happen
there are more than 1500 billionaires in the world, net worth 45 trillion. there is a lot more where that came from too.