Billionaires are those succesful business owners right? This people are a very business minded people , everything that can generate profit is another opportunity or another risk for them. They usually gets involved when a business sounds fair and legit. Btc is  a fast growing digital currency and it continuosly a demand in the market. I guess BTC already gets the attention of those people. Have you seen the movie "John Wick" Did you noticed they are using Coin (physical coin) as payment for every deals and transactions, I assume they got the concept and idea from bitcoin.