I don't short because I hate the company. I short because I believe the stock is overvalued relative to reality.
Poker taught me how to make decisions under uncertainty. Investing requires exactly the same skill.
Lehman Brothers has been using financial engineering to hide its problems. The firm is not as strong as management claims.
The difference between investing and gambling is that in investing, you can do research. In gambling, the house always knows more than you. In markets, sometimes you can know more.
The best investment analysis is the one where you do the work nobody else bothers to do. Read the footnotes. Call the competitors. Model the assumptions yourself.
Markets can stay irrational longer than you can stay solvent. But eventually, earnings drive stock prices. Always.