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.
I think many billionaires are investing some of their money in Bitcoin. Those people are smart and intelligent individuals that is why I'm pretty sure that they studied the system of Bitcoin and decided to invest that is why the Bitcoin is already clicking nowadays because of the investors who are investing here.