If your trading supports your lifestyle...you're a successful trader without guarantees you'll be the same next year or any other year in the future.
One has to define two things: the trader and the success I call the trader anyone who can make a living trading his own money. The success - probably if one can trade for a living for at least 10 years.
If one doesn't have a consistently profitable system within a year, he ought to find something else to occupy his time. This doesn't mean that he's solved all trading problems by then, such as actually following the system, but at the very least he ought to have reached an understanding of the nature of price movement.
There are some traders out there with 10 years or more that still do not treat trading like a business and continue to rack of loses. When you start truly treating trading like a business than the years of experience will start to count for something. The bar is extremely low for just the years of trading alone. Traders that have a written trading plan & follow it that would be a good point to start from. Some people have made a lot of $ through pure luck - problem is they can't duplicate it. Your on the road to success when you plan your trades & trade your plan. Your also a success when you have already made enough that you don't have to trade very often or at all if you don't feel like it. "The first 1,000 years are the hardest" Zeckzillatz 200 A.D.
"Trader" is a term used loosely on ET. It can range from HF guys to investors to swing guys to dabblers to complete bullshitters. For a day trader, it's once you have enough experience and success that you wake up in the morning knowing that you are likely to make money that day (and do). On days when you don't, you will still have observed all your rules and only took your defined signals and on the following day, you wake up with the same confidence as you would have following a profitable day. How long that takes is how long it takes, most never get there.
comagnum, If someone started trading in 2009, and had a very simple trading plan: Go long. He could make a lot of money "trading". Wow, he is a successful trader, making good money trading full time over the last 9-10 years! Is he really that successful and has a winning methodology? I would say not - I am that guy. You are right, it is pure luck, lucky to be in the right place at the right time. Unless one is truly tested in a normal market or bear market, one is not a successful trader no matter how many years one has been trading and making money. It is easy to confuse the bull market with trading skills. Best regards and happy holiday to you,