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?
This is because they don't trust bitcoin and see it as a speculative asset that might not survive in the long run. As time passes on, bitcoin keeps proving to people that it's a store of value and a hedge against inflation. However, there are some rich folks who understand bitcoin but don't have such wealth. They have being buying aggressively since 2020, example is Michael Saylor.
Secondly, the government have been spreading FUD those years that bitcoin is used for scam and they were against it. This circle bull run left most of them speechless as bitcoin proved them wrong. Look at how big companies in various sectors have started buying bitcoin aggressively for
thwirtheir bitcoin reserve after bitcoin hits $100k.