Over how long a period of time? And I know people who lost 50-100k a day doing it too. Proprietary trading for a financial firm is a job. Not a gambling job at all. But to think that you can beat a Fortune 500 financial company's multi-million dollar HFT algorithm on your desktop is a bit delusional. If it was so easy the big companies would be all over it, and they are, at your expense.
I get it. In the short term there is money to be made. With prudence and a system there is money to be made as well. But what was written in this thread about emotional trading and learning to control emotions and acceptable loss percentages etc. thats downright scary.
You have a VERY good point. I have been trading for a very long time, and I trained with one of the best traders ever who was one interviewed in the New Market Wizards, a few years ago I broke one of my rules by getting stubborn and not covering my short position in crude oil with a small loss, I was short 1 contract only and had a loss of $2000, instead of sticking to my stop loss and covering with a loss of $2000 I started adding to my short position on every little move higher, till without being aware of what I was doing , I ended up short over 20 contracts and the market kept going higher till it reached my pain point and I had to cover with over a $100000 loss, all in one day and it wiped out a whole year's profits of day trading. My point is we all can read about emotional discipline and sticking to the rules, but one bad day, one bad trade can wipe you out.
I have never repeated this mistake, I have my set of rules on a small sheet of paper taped to one of my screens, I follow it blindly after learning from my mistake, and I have not had a losing month for over 5 years, but most of my trades last days to weeks, I do not do much day trading.