Trading with no stop losses. You can’t control how big your profits are, the market will trend as far as it does. However, you can control and limit the size of your losses with a stop loss and a carefully managed positions size. Not having an exit plan if you are wrong can be very expensive when a trend takes off against your position and you start hoping instead of just cutting your losses and moving on.
Your opinion can cost you money. Trading your opinion against all other market participants can be very expensive. The market goes where it wants and when you disagree with where it is going it will cost you. Going with the flow in your time frame is the best way to make money. Fighting the flow of the market can be expensive.
Egos are expensive things. Inflated egos cause a trader’s #1 priority to be proving they are right and refusing to admit when they are wrong. It is very expensive for ego gratification to be higher on a trader’s list than making money.
Trading off predictions can cost a lot of money when they are wrong. There is more to be made by reacting to what the market is doing instead of predicting what you think it will do later. The future does not exist and it is expensive to pretend like it does.
Stubbornness causes small losses to become big losses. It causes a trader to make the same mistake over and over because they do not assimilate feedback. Instead they keep doing the same thing over and over and expect different results but keep getting the same results. Stubbornness is expensive.
Not having an exit strategy for a winning trade can be very expensive. It is possible to ride a big winning trade back to even. If there is no plan to lock in profits while they are there a winning trade can even turn into a big loser. Trailing stops and targets can put the profits in the bank.
Trading too big of position sizes for your account can be very costly because no manner how good your winning trades are you are set up to give back the profits with a few big losing trades in a row,
