Unlike the market cap numbers that get thrown around when people say X dollars "destroyed" from the stock market or Y dollars "gained", this isn't nearly as imaginary (or invented out of ether).
Depending on whether we're talking about real shorting, or put options, it's one of two things:
-
They borrowed expensive SpaceX shares, sold them, bought back for cheaper, the people who bought shares at the higher price paid for it.
-
They bought put options and exercised them. The bank or financial organization selling the put options paid for it.
Now I went to actually read the article and this particular number was #1, but I'm sure a lot of people profited through #2 as well (the wallstreetbets types).