Tulips Break 150ƒ
In 2013 (less than 8 years ago), the market cap of all Bitcoins was under one billion. The float was much smaller. Sergey Brin alone could have bought the entire market with less than 2% of his wealth. With the float small, the price could be propped up with a much smaller percentage than that.
Now the market cap of Bitcoins is over one trillion. Which means the bubble is more than one thousand times harder to prop up.
Quantitative easing - 12 years old going strong.