Because we don't know what "successful" means to every individual, we should divide traders into different groups. I think most traders can be found in one of the following groups:
Group One - these are mainly traders new in the trading business. They have read a book or two and they find trading very interesting, but they still don't know where to start.
Group Two - these are the traders who already know what is important in trading. They know it is important to have a trading plan and they know almost everything about the markets. But their lack of discipline and other important skills is keeping them from making money. They still lose money most of the time, and they keep searching for the right entry or method instead of looking in the right place - self-discipline.
Group Three - these traders are trading break-even or are making some money, but still are not able to make "a lot" with their trading. They have a good trading plan which they follow most of the time, but there is still something missing, preventing them from consistently making money in the markets.
Group Four - these traders are consistently making money in the market. They are able to find good trading opportunities, and they are following their trading plan in a very disciplined way. They feel comfortable with what they are doing and they are not worried when their equity curve goes down from time to time because they trust in what they do.
Group Five - these are the "high class traders" making consistent profits but, in addition to the earnings of group number four, they occasionally make "tons" of money with some of the trades they push to the limits.
Statistics tell us, that we have around 75% in groups one and two, only 25% are trading break-even or better (in day trading the numbers are even worse). Probably 10% of all traders are in group four, and only 2% in group five.
Now it depends on what "successful" means to the trader. For most beginning traders, being successful means they are not losing any more. It usually takes a few years for a trader to get into group three. I think it takes so long not because it is very difficult in the beginning, I think it takes so long because most beginning traders don't have the right orientation and they spend lots of time searching for the magic of a Holy Grail.
Once in group three, it again takes some time to move up to the next level. It requires lots of practice for each trader to find his best personal way of trading. I don't know if it is possible to tell how long it would take to get into group four, and many traders will never make it. But to be honest, I think this isn't important - it's your consistency and determination that counts. Making it up to group four is all a good trader will ever need.
Yes, because you can not count them together. 25% are trading break-even or better. The 10% and 2% fall also under the 25% (or better).