I think the most important factor for loss at trading is wrong strategy. The other factors are lack of knowledge, skills and experience. For earning profits you must give 100% dedication at forex trading.
Please take a look around, and feel free to .
There are number of reasons for having loss at business. Lack of knowledge/skill/market analyse, greediness, nervousness towards losing money etc etc. Now it totally depends on the person that what he is facing.
And there are still times when the trader himself lost from a reason he can't easily explain. Well, one can attribute it to the complex and unpredictable nature of the market. That is why it is advisable to avoid the market when it is highly volatile.