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:

1. They borrowed expensive SpaceX shares, sold them, bought back for cheaper, the people who bought shares at the higher price paid for it.

2. 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).