There are billionaires worth over $100 billion, and even more worth between $10 billion and $100 billion. So why haven't any of them bought most of the bitcoins? They could have done so, for example, in 2020, when the price of bitcoin was $5,000-$8,000. Bitcoin's market cap is now less than $2 trillion, and it used to be even less. Some multi-billionaire could have bought at least 10% of all bitcoins, but why hasn't anyone done so?
Because they already have companies and investment that give them profit that put them to Billionaire positions. They don’t need to venture on other assets if their current investment is already enough to generate good amount of profit.
I believe we have higher chance to attract millionaires and retails rather than billionaires to invest on Bitcoin because we are still willing to risk a lot for a huge gain.