I really don't think much of the billionaire's will be investing into bitcoin. Because they probably have already been making a good amount of profit through real time business. But more and more has started to invest into bitcoin related business as they have started to understand the real value. But billionaires, there were just a few that i heard of.
For me the rich ones are the ones whos's always making investments and if they know bitcoins is a good way to generate profit they will invest on it .I am an investor and i experience socializing and partnership with a rich people they thinks every opportunities as gold .I am more mindful that when many millionaores or billionaire's know that bitcoins is a good source of profit they would invest on it and they can afford some big amount to invest.