I think those millionaires who invested bitcoin in 2014 is most likely they will be billionaires right now because of its current price haha and those billionaires who invested right now  is going to be trillionaires sooner if the price is keeps rising. Bitcoin is getting famous world wide and mostly all of the people want to own a bitcoin and hold it for the future because it is good investment so i think billionaires will also bought bitcoin and hold it because it is a big money to them and a big profit.