well i think they are, there is a rumor that Zuckerberg is investing in bitcoin. And hell yeah they know that it exist.
as far as i know billionaires invest also in BTC, like bill gates who known as one of the richest people. And most billionaires want to invest their money in biggest profit. rich people want to become richer and if they follow btc and learn more about it billionaires willing to invest on it.