At some point, they will have to sell their positions at a loss, making them new sellers and no longer buyers, and this will drive the market down further. Sellers will continue to enter the market either as new shorts or as longs forced to liquidate until some point when more buyers start coming in. These buyers will be a combination of new buyers,profit-taking shorts, and new shorts who now have a loss and will have to buy to cover their positions. The market will continue up until the process reverses once again.