The 'fun' things with shorts is that they have a fixed upside and infinite downside (ie if you go short $1000, the most you can earn is $1000, but you could lose any amount of money and much more than you invested. This is the opposite of buying a stock, where if you invest $1000, the most you can lose is $1000, but there is no limit to how much you can earn). You can be perfectly right 9 times out of 10, but that 1 time you're wrong can quickly wipe out everything you made from being right those 9 times.