Well they enjoyed a historical return off of the people who bought too late. It's not like their money spawned out of nothing. They sold their bitcoin to someone who hasn't been as lucky, because they bought when the price was at its highest, ind the hopes that the price would continue to climb.
It's pretty much a zero-sum game. For someone to earn something on crypto, someone else has to be left either losing something, or holding onto something in a desperate hope that the price will explode again.