Quote from dbphoenix:
1. Because they think it looks easy.
2. Because they think they're smarter than they are.
I agree, sadly I've been part of the 95%+ that fail each year. At first I thought it would be easy and I thought I wouldn't be like everybody else. Then I got my arse kicked by the markets for a few years in a row. I never lost interest and kept coming back and trying harder even though I wasn't making money (which makes me feel like a schmuck, but oh well). In my most idiotic recent blunder, I bought a call option on AAPL, sold it at a loss the other day, now it came back strong today, so all that money I could have made off it is out the door. (SIGH) I don't want to completely give up on the world of stocks, since I know the money can be good when you invest long-term and have patience; but I've admitted to myself I don't have the self-control to let my profits run and to have discipline when stocks start to turn south, when I trade.
Now my next plan of attack is to eschew trading until I reach $10k in both my trading and IRA accounts, then I want to buy good stocks which I know will be around in 50+ years and also buy covered calls on them, so I know my potential profits in advance. Then if the stocks aren't in the money at expiry, I made extra off the premium payment and dividends. Also, I will keep studying and learning.
Thus, to everyone I say, if you do poorly at trading, don't feel bad, you could have been me! But, if you fail at trading, there are still so many other fields to go into and other things to do in life, so don't feel bad.

I am 28 years old, so luckily the amount I lost wasn't that much, but I was the textbook putzy example of doing everything wrong that I could have done. I didn't diversify, I didn't have enough starting capital, I tried to use options to get bigger returns (which are possible, but can also wipe you out with bad luck), as well as other 1/2 assed methods. But, on the plus side, I learned from my mistakes and see that perhaps I need to find a career in another field, and give up trading. Or.....I can find a company I hate and get a job managing their fiances, and they'll be broke over night! (Sorry, some self-deprecating humor)