> Shorting tends to be intrinsically harder because the market goes up over time and Americans are generally optimists.

... and the market can stay irrational longer than you can stay solvent.

I remember once I tried shorting a stock, of a market leader in my area. I knew the field well enough to see that they were trying to fudge some numbers and their quarter was _not_ as good as they had claimed it to be.

But sadly the market didn't see this and the stock went up. E*Trade started pushing me to cover my positions, and eventually I ended up losing a 5-figure sum (nothing earth-shattering, but still a good chunk of my cash).

After I had bought it all back, slowly the market realized what I had seen and the stock dropped as I had expected. Unfortunately I did not have the deep pockets to stick around long enough; all I was left with was a hole in the wallet and a hard lesson learned.