While everyone has indicated good reasons for the failure amongst traders, I believe that they only equate to a very small percentage of the 10's of millions of traders who have quit over the last 20 years.
The answer to the question "why do most people fail?" is due to the lack of 'TRADING EDUCATION', not the lack of 'FOREX or STOCK MARKET EDUCATION'. The title 'forex trading education' is absolutely wrong, it's in fact misnomer. It should really be called 'forex education, stock market education or whatever education, but not trading education as there is no actual 'trading' information included within the written data.
The reason for this is that most people don't know about or understand trading education. If you search for "forex trading education" on the internet you will find there is none, all you get is the same forex websites if you had typed in forex education. Again, if you type stock market trading education, you will get the same websites as a search for stock market education. Not one single site from millions of sites returns any trading education, not even the good websites like FPA and Babypips.
First you must understand the meaning of trading in trading education. Trading education starts where forex education finishes. Forex education deals with all facets of the forex market up to locating entry points. Trading education on the other hand starts from trade execution. It is about being able to look at a chart and have a good idea about what's going to happen. For instance, Is the trend going to continue or reverse? Are you trading with trader support or with trader weakness? Does the future of the trend look strong or weak? Should you take profit or let run? All these questions can be answered to high degree of accuracy with trading education.
While knowing forex education is always advantageous, the truth is it not required to be a successful trader. If taught trading education correctly any new or experienced trader can become very successful without knowing any forex education at all.