Bet your shorts, page-4

Shorters effectively borrow shares at for example purposes $1 per share in Bet's case. Then when/if the share price drops to 90c they the shares and make that 10c per share profit minus fees etc. The lower it goes the more they profit. If the price goes higher instead of lower they are forced to buy the shares earlier then they might have intended or face infinite loss potential. Because they are buying shares it can 'squeeze' the share price higher. Vicious circles form and GME is the most famous recent example but there's been others. That's my basic understanding and apologies if there's technical/terminology errors