simple
Make money = buy low, sell high
normally = buy low, then sell high
short selling = sell high, later buy lower.
Assume they sold average around $30 or at 140% of shares

lets say at $5 they cheebai dont want to buyback which is what happened.
at $5 they make
profit per share = 30-5 = $25 per share minus the interest of borrowing the shares
but since they cheebai greedy wanna push down lower and got burnt,
they sell $30
WSB reddit crushed their balls and pushed 10x more higher, now need to buyback at $400

profit per share is = 30-400 = - $370 loss

shorting means you sell high price first, later buy back cheaper price.
but now they have to pay 10 times higher that price for what they have sold.
so instead of making 300mil or so, now they gone negative 3billion
essentially buy high sell low BODO